After about 12 years of not autocrossing, I've decided to get back to it, in STX. My old setup was -2.2 to -2.5 front camber with 6 deg of caster and -1 degree in the rear. This was on 15x7.5 wheels with 205/50/15 Falken Azenis tires. I've decided to make some changes and Looking for tire pressure recommendations, The initial plan is to run 225/45/16, Yokohama A052 in the front, on my 16x8 inch wheels with about the same camber but maybe increasing the caster to 7 degrees. In the rear, I"ll stick with -1 degree but I'll be running 205/50/16 in the rear. I'm thinking Zero toe F&R but might start with just a little toe in in the rear.

I can probably get as much as -3 degree of camber in front, if I keep the caster down to 5.5 or 6 degrees but can probably get the caster up as high as 8 degrees, with my K-Mac plates and still get -2.2. 342 lb springs in front, 350, in rear. OEM front bar and Webb Motorsports rear bar, about as stiff as a 22mm solid bar. TSW/KW V3 coilovers. Quaife LSD.

I seem to remember reading a test suggesting 34 to 37 psi but can't even remember what was the front and what was the back and of course I have a completely different setup and maybe not a very similar type of car.

 

OK, welcome back to autocross. How soon are your events? Is there an event where you can test and tune to get tire temp readings? What is adjustable with your suspension once you do alignment? Shocks, swaybars?

On alignment in general more front negative camber the better up to about -3 to -3.5 degrees, no need to go any more negative until you get tire temp readings to see where you are because it depends on your courses and your driving style how you use and wear the tires with a given camber setting. Those who drive more smoothly and less aggressively will not need more camber because weight transfer is not as severe under load.

Sample autocross alignment for MINI
Front camber -2 to -2.5 degrees, more negative increases inner tire tread wear for daily driving
Front toe Zero to 1/16" toe out. Either is OK but slight toe out helps with turning response without being overly darty for street driving
Rear camber -1.0 to -1.5 degrees, could be as negative as 1 degree more positive than front camber. Again set it and check tire temps to see how the rear tires are being used. Set rear swaybar for controllable oversteer or minimal understeer.
Rear toe usually a little toe in like 1/8" is fine for straightline stability.
Caster does not need to be excessive, not for drag racing where you may need more. 5.5 to 6 degrees Ok with what you need for front camber setting of choice.

Yokohama A052 are good tires, Since you are returning to autocross you will need to get acquainted with driving and with how the course is designed and setup in your area. Maybe you are driving in a different region, maybe the surface is different, maybe the course designer is different that you past events. So pick tire pressures that are middle road and adjust once you do maybe two runs and see where you are at.

I chalk the sidewalls of the front tires in four places and try front pressures of about 36 psi cold and rear of 32 psi cold. Usually I want pressure that will give me some room to adjust, not too high as pressures will rise as tire heats up. If it is early and cool then higher pressures OK but if midday and warm then lower pressures to start. Use a probe style pyrometer to check inner middle and outer tire temps especially on fronts to see how to adjust pressures. If middle treads are higher then let air out, if outer treads are hotter then I try to adjust to bring middle and inner treads closer together. Usually with hard turning the outer treads will be hottest so I don't worry of that much. I want inner treads to heat up the most since they usually remain cooler.

Some drivers will use water spray to cool the tires if they feel the tires are getting overheated and greasy. It's a matter of choice and if you have two drivers in a heat it is possible to benefit from cooling. With one driver I have never needed to cool Extreme Summer tires with the short courses I run. Race tires could be a different matter.

As you are returning to autocross (even with national level experience) it is always a good idea to get some input from "experienced instructors" in your area or at a driving school. There is usually much evolution that happens with driving instruction over time and sometimes a different approach that varies from one instructor to the next.
I have done Evolution Driving School every two years for 10-12 years with some of the best instructors, I have noticed that the approaches have changed and/or my ability to understand how the school functions or approaches learning is deepening. I look at the courses (of the different Phases) and how they are designed to teach driving skills and how to test driver adjustments. To understand a course well allows you to drive it well no matter your setup. Setup helps with car control and should be suitable with your driving skill.

Alignment helps with making the best use of your tires, warm them up evenly to get the best wear and grip levels given your driving style. I rarely run the exact same tire pressures on all four tires, it's all based on tire temps for a given event, conditions, and driver.

Glad to see you posting.

 

1. First, Thanks for the reply. Lots of good advice for many autocrosser's.
Hmmm, looks like I screwed up the reply. People will just have to figure out what was minihune's reply and then my response. 1, 2, 3, 4, 5, 6, 7

 

FWIW, I am running an STU setup with all the trimmings, including 8" rims - YMMV. 225/45-17 Yoks.

1. I have observed the A052 pressure increase 7 pounds from cold to warm, growing from 33 to 40.
2. The tires on the 8" rims seem quite happy at 37-39 pounds out front. They do not deform and do use all the tread.
3. I run -2.1 camber at all four corners.
4. If I go more than 2.5 degrees out front it hurts acceleration - even with the Quaife. It doesn't help braking either - there's a point of no return.
5. I've a pretty stiff RSB, and handling is neutral with balanced tire pressures - if I want the tail to wag I go as high as 44 pounds out back.

Here's the tire wear at 39 lbs - after a Dragon run.

All the best.

Charlie

 

OK, thanks for your reply and this discussion which brings out a few points that aren't brought up enough. I adjusted my camber spec range as I was out of the limits I use.

2. Take advantage of the Test and tune to try things out and see what fits you best. I'd be much less concerned about times and more about getting the setup dialed in. As you had mentioned these will be new tires for you so that will be something to note. I think you will find that compared to 12 years ago the newest Extreme Summer tires are quite capable. On a 30 second course we have street cars on Treadwear 200 tires that beat or are within 1/2 sec of cars on race tires and it's not driver experience that accounts for that result. Perhaps some may be due to slower top speeds, many more very tight turns, a short 0.4 mile course and lower ambient temperatures, all of which may reduce any advantage race tires have. You bring up a good point and that is with DOT treadwear 200 tires does one benefit from heat cycle and shaving.In my experience I only heat cycle R compound race tires and only because a roller does a better job at evenly heating the tire than I can do with driving it on the street. Other things I do to make race tires last- don't overdrive them (late brake, sliding, overheat), monitor temps and try to even out gradient of temps during the event, save race tires for races not fun runs, keep them clean (inspect, wash and store well), Flip and rotate tires when possible (works best with square setup even with staggered wheels), keep track of which tires are used on which corners (more important with square setup). Borrow a tire pyrometer if you have to, I lend mine out as needed.

3. Your alignment approach is noted and may be more advanced than most. I'm spoiled I have a Quaife LSD so I stick to the basics and that seems to work OK for me. I have run -2.4 degrees front camber. You need to see how the entire setup works for you before second guessing what parts may need adaptation. My goal is usually dial out understeer and try for controllable to minimal oversteer. The rule of thumb at Evo School is all understeer no matter the car, is something the driver has control over which means instructors driving the course never get anything more than very minimal understeer and manage any oversteer to keep things in balance throughout each run. it helps when you drive at 80% too. For chalk I tend to use sidewall chalk as it is easy and cheap. Note that chalk disappears when rubbed off but you don't know how much you are actually at that limit, i.e. enough to rub it off but not enough to create any heat. I place more value on temperatures than chalk rubbing.

4. Remember that tire temps relate to the driver and the exact course under those conditions. We run four heats and all under very different conditions from cool rainy in the morning to blazing hot in the afternoon or the opposite. If it rains or is cooler I may run slightly higher pressures but the fronts are always higher than the rears.

5. having the sprayer is a nice extra if you need it, or you can borrow one in a pinch.

6. To me, no one is so solid that he cannot learn something from an educational experience such as a Phase 2 Evo School or a Challenge Course. They are designed for no one to be able to max out driving it the whole day, most of us can't get near to feeling comfortable what we are asked to do. Yet it is possible to do really well under those conditions, check out the instructors. Why because they know the course and what is required. They will tell you what to do or look out for but you need to realize what to do and execute. At my last Evo School the instructors were mentioning later in the Spring they were going to a midwest region where in Phase 2 they had 8 students who were Solo National Champions (no pressure). You can't fine tune things enough with this type of sport we do.

7. Staggered setup- Is fine but levels of grip will be different. FWD with more front grip is good but they also reduces grip in the rear relatively so just watch out where the balance in handling is. Use the suspension adjustments to dial in or out any understeer or oversteer. Usually I try for shocks slightly softer in front to a middle setting and stiff in the rear for less understeer, I run only a rear swaybar set to a medium setting then adjust from there. Even with a square setup levels of grip are different as you never really fully use the rear and it seems like the fronts are overworked on most runs. We do see other FWD cars attempt wider front wheels and tires than on the rear so it is just getting the balance tuned in for you.

Wheels and tires-

You have 16x8 wheels both front and rear
205/50-16 fits wheels 5.5-7.5" wide, perfect for 6.5" wide rims. On an 8" wide rim they will be stretch fitment so you will need to see how temps run. The other way to do it is use a 16x7" rim in the rear. The 16x8" is theoretically 1.5" wider than a perfect fit so the stresses on the tire will likely affect wear and grip levels. Also in my mind you are carrying more weight in a wider than perfect rear wheel, but this is a minor point if it gets you the results you want. Another possible option is to run a square setup and take advantage of tire rotation for wear.

Thanks Charlie for your comments

 

Thanks again for the reply's from both of you. Even in my inactive years I have sporadically read may posts by both of you.
I will be starting my pressure's at 36 F and 32 R.

2. I will disagree, on the heat cycling, in my case. These AO52's will be my autocross tires. I will not be driving them, on the street, with the possible exception of driving them to local autocrosses. The tires, would be green and not have been heat cycled and scrubbed in by driving them, on the street and therefore be, not as competitive in it's early life and easily damaged, even in a normal autocrosses, by over driving them. Back in the day, I would drive my competition tires, on the street, for at least 30 min. and slowly bring them up to temperature, then either park the car for at least 24 hours or take them off, for at least that long. This, wears off the mold release, on the tires and cures the rubber, making them more durable.

3. With the extremely rare exception, everyone would, including me!, benefit from an EVO school, more seat time, experimenting with setup and driving techniques.
I have a Quaife. I was probably the first one, in the USA, to get one for an MCS in Dec. of 2002. Documented, on Mini2.com, though Helix13 beat me getting it installed by a week because I didn't have the right bearings to start with. An OS Giken, will put the power down better and is even tunable to conditions/driving style. Two things I need to mention here. 1. It costs, 50 to 70% more, than a Quaife. 2. It will wear parts out over time, unlike a Quaife will do during it's likely lifetime (likely more than 3 decades). The Giken will have pretty much yearly maintenance costs as it needs to have it's very expensive gear oil changed at regular intervals, I've read 10 thousand miles and every time you pull it down to adjust it or replace worn parts, it's pretty much all the same labor costs of replacing the clutch. The Giken will be faster on an autocross course, the question is how much faster? The answer would be dependent on, #1 the course, #2 how lead footed you are. I tend to be somewhat lead footed and would benefit more than someone who is extremely smooth.

5. Test and Tune, 200 tread wear tires, Summer in central Va. a Sprayer is a near necessity, unless I want to bake my tires and degrade their then and future performance.

7+ Wheels and tires. Yes an ultra light 15x8 will always be lighter than an ultra light 16x8 and less weight is good. Most of the time a wider heavier wheel (20-40%) will be better for an autocross than a narrower light wheel. Generally speaking, Do not give up wheel width for wheel weight! Your implication is, as I see and read it, is on a 205/50 tire, the performance will be better on a 6.5" wheel. From the stand point of any serious autocrosser I've know of, in the last 40 years, NO ONE, would agree with that! In fact, almost all would say to use at least the Rim manufacturer's widest recommended width, in this case 7.5". Some tires are more tolerant of narrow rims, I hear/read, the RE-71R, is one of those and probably wouldn't give up much time, if any, on a 7" wheel. On the other hand, a BFG R-1.5S is said to be much better when stretched. In the case of a 225/45/15 the preferred rim width is 9". From what I read, the A 052 is somewhere in the middle, like most tires and I have run 205/50's on both 7.5's and 8's, many times, with no issues. Tires are springs too. A wider wheel will increase the tires effective spring rate and allow you, in most cases, to lower your tire pressures and there fore increase the tires traction potential. My 15x7.5 SSR's weigh just over 10 lb. and My 16x8 Volk CE-28N's weigh 12.1 lb. As in wheel weight, don't sacrifice a better tire for a lighter tire and don't choose a better tire size, in a lesser tire over a better tire in a slightly less than perfect size. If I had my choice I'd run a 225/45/15 RE-71R or a Yoko A-052 on a 15x8, in the front but I'm choosing what I think is a better tire instead of BFG's better size. Would I be better of on 205/50/15's than 225/45/16's? I don't know! May be course dependent, I had to start somewhere and chose a staggered set up, as that is what I really want to do even though I'd rather do it with 225/45'/15's in front and 205/50/15's in the rear, they just aren't available in my tire of choice, right now.

When I started autocrossing, in 1976, one of my most effective mods, of many, on my 1973 Datsun 240Z, was to swap out the 14x5.5" wheels with 175/70 tires for a 14x7.

Maybe interesting tidbits? I ran Yokohama A001R's , their first performance tire,when they came out in 1981, maybe 82?, on my 1980 Dodge Colt RS with twin stick Transmission (8 forward gears!) Wow! what a radical change from even the best of any other "street tires". I also ran the very first Bridgestone RE-71R, that I'm aware of, in 1991?, on my 1989, Plymouth Colt Turbo. Boy were they super soft! Wore them out in just a few events and went back to Yokohama A008's or 8R's I think.

 

That's pretty much where I run my pressures once the tires have heated up: 36 to 37 in the front and 31 to 32 in the rear.

 

This discussion is a good one. Yes there can be different approaches and each with good points.

The thing about tire pressures is it's just a starting point and relative range that you can apply to your own situation. We all live in areas where the weather changes and varies sometimes by the hour. What works may change rapidly under those conditions. The other point is when racing our courses and our driving style will be a huge factor in what pressures may be most helpful in using the tires for the most grip and the best wear which is always my focus. So there is never an autocross where I do not check tire temperatures and adjust the pressures. I usually have a good idea of where to begin the day, I make some adjustments by Run 3 then I can usually leave them for the final two runs. I check temps with each run so I know which side is getting hot faster sometimes needing to let air out on the side getting higher earlier while the other side I let build up and stabilize. Also our driving style affects our tires greatly and may determine wear and grip levels with each run.

2. Heat cycling is a tool to help with getting tires ready for competition and to allow changes for better wear. I use them for race tires only as I street drive my Extreme Summer tires for at least a week before events to remove mold and scrub them in. Race tires that are heat cycled I also scrub in and let them rest at least 24 hours but usually a little more than that. I clean and cover race tires and store indoors in air conditioned area and give them a good scrub wash and wax the wheels each season once or twice at least. I had tried heat cycling my race tires on the street and even after 20-30 minutes of vigorous driving I could never bring the temps up enough or evenly to make it seem like I was doing anything worthwhile. Fronts would heat up especially on the outer treads while the rears were essentially cold. Also I get weather changes like rain quickly and unpredictably and there are road hazzards and debris that could spell trouble. We had one autocrosser who was street driving on Hoosier A6 tires and it rained, he lost control and totalled his FTD Porsche 911.

3. Although I am a proponent of driving schools they are not without some downsides and caveats. True they have the potential for growth and learning but offer perhaps not as much value for those who approach it as a passive learning experience. At least Evo Driving School will stretch students to their limit and is why I think retaking those courses can be beneficial. Similar to a master class learning experience where you have skilled people who can fine tune and hone skills with insight and move to a higher level. One thing that can happen with driving is we get set in our ways which are comfortable for us and we get some success and think it's all good. Maybe we have some bad habits we pick up and not think it's a big deal. Sometimes in those cases we really don't know what we don't know. We can learn where our gaps might be if we expose ourselves to others or other experiences that might open our eyes to different approaches or maybe catch our attention by the gap in our driving times and someone elses. Sometimes the difference is not so large but there is definitely a consistent difference in run times.

7. Wheels and tires- For the optimal wheel size with a given tire size, yes you want to find a balance between cost, weight, fitment (perfect rim width vs wider rim) and personal performance (does it help you). I do lots of tire sizes on various wheel widths and never used a 205 tire on an 8" wide rim for competition, the opposite is more true, wider tire size on more narrow than desireable rim. In either extreme I am concerned about stress on the tire, uneven wear, and how the tire heats up with loads and use for my given courses which are heavy on tight turns at speed. In the end you find what works for you until another better alternative exists but I have stuck with the same race wheels over time and tried many possible tire sizes to find the sweet spot for my conditions. Both tire and wheel weight are only one consideration and part of the equation to find what works. As you mention we often have several possible approaches and some good race tire choices in Extreme Summer (more than in the past). I always look at tires first and try to find one that will work for my setup and courses then look at possible sizes that will work with the rims I have (15", 16", 17"). In your case you have many of the best and lightest wheels so a little difference in weight is not that crucial. I usually won't worry much about tire weight per se if I can get the right fitment and I can get results. I feel I can learn and adapt with driver skill and work with whatever setup I choose. If you know your tendencies and preferences well then you can select an approach to setup and fitments that would bring you close to what you prefer. In Evo School the instructors just drive what you give them and get consistent quality results that looks effortless. I once asked them during Phase two about exact tire pressures- the response was not to worry too much if overall things are working OK. Focus on your driving not the little details in the moment. Many of our autocrossers are more intent on modding and changing many things in the course of the season. Sometimes not allowing themselves to get adjusted to a new setup before changing it. My approach is the opposite, I might find a setup is worth exploring then I stick with it making minor adjustments see how far I can take it. Of course the other part of the equation is that with each event the course changes so our assessments are constantly colored by all that takes place.

When I started in the early 2000s there were 5+ Datsun 240Zs on race tires at my events. The best was always FTD and some 12 seconds ahead of me on a 1 minute road track course. 3-4 years later at a Stadium parking lot course I would catch up to be 2nd to him on raw time of a group of 90 drivers with still much to learn. We still have a few 240Zs that run and they are among the most competitive cars out there when driven well. Very old tech. I remember in 2013 when RE71R was new, I bought them in 2015. RE11 arrived about 2009?. Any word on the new Bridgestone RE71RS?

in any case I think the Yokohama A052 is worth the try, the newest Extreme Summer tires on tire durometer measure very soft approaching cold R compound race tires. Whether they may heat cycle and eventually harden with use needs to be evaluated and how long that process takes. I don't mind wearing them out before they cycle out or get both to happen at the same time.

 

I run track days with a basically stock GP2 (wheels also 7.5"). No Auto-X. Limited car street time, drive to and from the track. Got A052s (215/40/17) in Feb, ran one track weekend in March (2 days, 8 total sessions) before COVID. Ran one day (4 sessions) this last weekend. I have been running 37-40 psi F and 30-32psi R hot. Use chalk and pyrometer (but not religiously). Pressure rise a little more than stated below - but track not Auto X. Tires have very high grip - can out corner many other cars of high pedigree. However, lessons learned (to me). 1) A052s demonstrated high rate of wear. Suspect would have gotten 5 track days out of them, IF not for; 2) the (most heavily loaded) right front tire threw a major piece of outer tread - a major chunk (~20% of circumference) and some chunks in other outer areas. Did not deflate. Tires had been swapped front to back after 1st day in March. Same track, same counter clockwise track direction March and June so both right sides get highest loads. No significant rumble strip excursions - no off track events. No street pot hole events I can recall. Total of about 1,000 miles on the A052s (with track days). I think my situation exacerbated by 1) stock camber (~-1.5) and no heat cycling. I may go back to AD08Rs or try the new Falken 660s (but make sure I heat cycle - either driving myself or at shop prior to install). Recommend have camber commensurate with performance duty and heat cycle them - but suspect will be high wear. The price one pays for grip. (Also remember these start with low tread depth - 7/32.)

 

Thanks for your comments. Track alignment will give you the best handling and performance with the best wear for track use but wears quickly for daily street use.

Chunking tires-insufficient warming of the tire

• Tire chunking is primarily caused by insufficient warming of the tire before driving it hard. Next time take a couple of easy laps to warm the tire all the way through (not just the tread surface, but the entire tire carcass) before pushing them hard.

Try easy warm up laps to get your tires to a good temp before driving hard on them for track use- this helps with grip and with wear and may reduce risk for chunking. Chunking also more likely with tread blocks that are deeper when the tire is newer. Shaving down the blocks may help the tire perform better on the track. Driving approach (more aggressive) also plays a role in how you use and wear your tires and brakes, a smoother style will help- get some feedback and instruction at the track.

Some links on track tire wear-
https://nomoneymotorsports.com/2019/...tires-post-35/

 

Thanks for feedback Minihune. I usually take is slower initially than most in my run group and take a lap or two to get up to speed, but concur it could not hurt to even be more gradual and religious about it. 052s were pretty much worn down almost to tread wear indicators so tread depth not the issue with them. (However I believe tread depth did contribute to some micro-chunking on my previous set of AD08Rs early in their life.) Also agree with driving approach, which I told my friend I was likely a lot more aggressive than him and showed on wear I was getting on the 52s vs. his experience in his R53 Mini track car last year (which he runs with camber plates and -3 or more camber) (but they were high wear for him also). It is pretty easy to abuse the fronts on a FWD. I did have instructor with me and we were experimenting with some techniques but I was not really even that hard on braking as I could have been. However, the track has some reasonably high speed high load corners with little to no braking on entry and right front taking the brunt of the speed scrubbing - I think a factor also. Thanks for the link also - good info. Cheers.

 

Update. I ran a test and tune and an autocross both, July 4th weekend. I wasn't able to get back to my old alignment specs and had to settle for -2.2 camber and 5.85* of caster. I think the reason was I'm about .5" higher now than I was 12 years ago. Checking tire temps, every thing looked good but there was about a 2-3 minute delay after crossing the finish line before I could get the readings but they were very even with 37F and 34 rear. Rear camber at -1.2 with a little toe in but I'll be changing that to -1 and 0 toe this week. I made ~ 14 runs apx 55 seconds each and wore off 3/32, of my front tires!!!! I have already ordered two more 225/45/16's for the front, that I'll save for rain tires until the first two are done. Luckily I have extra 16x8 wheels.

The Front tires were a little more worn on the outside, than the inside, maybe 1/64". The car was tight, had a long 65mph slalom with no sign of looseness, on any of the runs.

 

Important! Another update. Apparently I was measuring the tires tread depth wrong and hadn't done a before and after measurement. So, in fact, I only wore 1/32" off that first weekend. I have since driven them to and from another event, 2 1/2 hours away and made 6, 40 second runs and can see no additional tire wear.

I did do another alignment before the trip. Now at -2.4F and -1.0R with zero toe at both ends and the car is balanced just right for my taste but I certainly have to pay more attention to it on the road.

 

I need some guidance on pressures eventually but for now which size should I buy ?
My car is a summer fun toy, occasionally used on track 3-4 days a year but mostly on road

I am looking to purchase some A052 for dedicated track days, im inclined to buy 215/45/17 as the currently fitted AD08R,
but also I’m considering 215/40/17 and perhaps even 225 with a Slightly wider rim.

I’m tied to 17” rims due to gp2 calipers fitted to my r59 roadster so cannot go any smaller.
I also need road legal rubber to drive to the track, And have used Ado8r happily for last 5 years but no longer available in Europe
I have picked up one of the last pairs available so do not want to kill them too quickly on track over the coming few year's

7” wide rims currently on bilstiens b16 ps10, quaife diff, super pro front and rear arb, gp2 camber
buying some 7.5” will be a big investment, will it allow a significant improvement on similar sized tyres?

Other factors to consider currently, running manic stage 2 but long term aim is for 280/300whp So feel the extra tread width is warranted
tracks I visit are generally fast with few tight corners, mainly Bedford and Silverstone.
https://www.pistonheads.com/gassing/...&f=18&t=515378

 

Sorry for the slow response. For best transitional response put some 215/45/17s on some 17x8's but if you can fit them, get the 245/40/17's on a 17x9, for the best overall performance.

 

Have picked up 215/45/17 might run a mixed set eventually,

what is the lowest Air/outside track temperatures that people are comfortable running these ?
lockdown ends for track days in the uk 31st of March and I have that day booked up

plan b is take out some well worn Ad08r that are currently on the car

 

I would not run the A052 below 45 degrees Farenheit ( 7 C ). The tires do not reach operating temp. Mind you I autocross - perhaps a more gradual warming during a track day might be kinder to the tire.

Cheers,

Charlie