As i am in the market for R compound tires for the 2009 autocross season, I have been collecting information on what is available, in what sizes, through which vendors, and at what cost. I have compiled this information into an Excel Spreadsheet which includes columns for maximum speed in 1st and 2nd gears ('05/'06 Getrag). OEM tire sizes are included for comparison.

The Spreadsheet should be included as an attatchment to this post.

I have included track-oriented tires as well as the more autocross specialized models. Please let me know if I have overlooked any of our options. I have searched for information regarding Avon Tech RAs for instance without success.

For sizes, I have listed the most commonly discussed on NAM, some which seem like they ought to fit a stock MCS, and at least one which does not seem as though should fit, but is currently being used to great effect by at least one prominent member of this community. Please inform me if I have omitted workable sizes, or if I have included sizes which are known not to work on a GS MINI. I would like to expand on the information presented by noting which tires: (1) fit stock wheels without issue, (2) fit without issue given the extra 0.25" offset allowable as per SCCA stock class rules, and (3) rub suspension components, but can still be used safely.

I hope this information proves to be useful to someone on this board. It's impressive how many choices are available when they are all laid out together. Thanks in advance to those who are able and willing to help me improve this resource.

Edit: I have left out columns including vendor information and online pricing as they include non-NAM participating vendors.

 

Careful consideration needs to be taken as to the surface type you are running on. Smooth asphalt, course asphalt or concrete. I don't know your experience level. The question you need to ask yourself is “are these new "R" comps necessary”. Are you competing against others that are running them or do you just think you need them? Locally I run street tires and switch to race rubber for National Tours and other big events. I have beaten people on race rubber using Falken RT615's 215/40/16's which are my daily driving tires. While not the best tire they get it done @ $360 a set. The Bridgestone RE01R is an interesting tire. Rated 180 tread wear they appear to be very soft. I would say they are a faster tire, but I haven't used them. Optimal size would be 205/45/16, $544 with the $100 SCCA rebate. Street tires make you drive smarter and don't mask your bad driving habits.

 

I participate locally with the Cumberland Motor Club in Maine. We use SCCA classing rules (some exceptions, but they don't apply to GS). Our venues are small and have immovable obstacle issues which make short, tight, technical courses the norm for us. I am finishing my rookie season and will have attended 8 events averaging 7 runs of 1:00 or less. Our venues are asphalt ranging from medium to coarse. I'm hoping for a similar '09 season in terms of participation plus (crossing fingers) an EVO course at the beginning of the season.

I've done this on my OEM Euforias which are now just to the wear bars on all four with noticably (but not extreme) increased wear on the outside shoulders. I will use them for my last two events of the season, and they will be replaced with PZero Neros once the snow tires go back on.

Our GS class includes three MINIs. MINI #1 makes it to almost every event, typically wins class by three seconds or so, and uses Nitto NT01 purchased lightly used and has gotten two full seasons plus a couple of SCCA NER events at Devens out of them (should give a general idea as to how hard a CMC season is on tires). MINI #2 is on Victoracers. I've managed faster time at our last two events, but with cone penalties. MINI #3=me. Every now and then we get a father and son with Yoko A048s, but if the forcast is good they bring a Catherham and a Europa instead.

Our club is unusual in that we allow ride-alongs, so I have a lot of passenger seat time in MINI #1, and the driver rides along with me at least once at each event, so I do have some understanding of the differences in terms of auditory feedback and break-away characteristics, and of what I will be losing in switching to stickier tires.

I've thought that perhaps unshaved track-oriented tires might be an interesting compromise between street tires and top tier R comps. Would they not provide a touch more feedback at full tread depth and autocross temperatures, then become grippier as they wear down (and my skills improve in order to put that grip to use)? Feedback on Toyo RA1s suggests that they should behave this way, and last a very long time. My only worry is that I might later regret not going straight to Kumho V710s. I will be using R84s/X-Lites/V-Spokes/Monzas.

Any feedback would be appreciated.

 

If you're going to R-comps, you have to ask yourself what the point of doing that is. If you're trying to be competitive with the index, going to National Tours, Prosolos, or Nationals, you pretty much have two choices, the Hoosier A6 or the Kumho V710. If you're just going to R-comps to go to R-comps, you'd be a lot better off just getting some non-R-comp Potenza RE-01Rs and running a street tire class if your region has one.

A lot of seasoned veterans will swear by Hoosiers. I'm an exception because I'm too cheap to have ever tried them out. I'm currently the only mini (in GS) signed up for nationals on Kumhos. Anyway, I've heard of people cording their A6's in 19 runs. I've just started on my 2nd set of Kumhos after nearly a year of events (75+ runs - never flipped). There's still a decent amount of rubber on my old V710's, and only one of them has a half-dime size nick that has exposed the cords. Much better $$/run, and if you look at a lot of performance tests, the two tires seem to trade off on strengths/weaknesses. The Hoosier is supposed to be a bit more sticky and have a sharper feel to them, the Kumho is supposed to be more forgiving and easier to find the edge to. In the end, if you're starting out on R-comps, just get the Kumhos and avoid the debate. Any potential trade-offs will be felt in your wallet. Good luck.

Edit: I forgot to add sizes for GS...

Hoosier: 205/45R16 and 225/40R17 seem to work well according to nationals-level drivers.
Kumho: 215/40R16 is what I run. 225/50R16's fit in front, rub in back. Try the 225 front, 215 rear combo at your own risk. I went into ice mode (I have an '07 w/DSC, FYI) several times and felt it was not worth the risk. It felt mushy, anyway.

 

I would stick with the street tires on the surfaces.

AZENIS RT-615, 215/45R16, 23.6" tall, $97 Vulcan tire. These have been my last 2 sets of tires for street and ax. They have stiff sidewalls. I can run them at 32 psi and not get on the sidewalls. As a reference I would run 42-45 with Hoo$iers. They are wearing evenly across the tread on my car which has a stock camber setting of -.4 and the shoulders are in good shape. The reduced diameter gives better acceleration which would be good for those short tight courses.

Direzza Sport Z1 Star Spec, 205/50VR16 24.1" tall, $103 tirerack
I have heard a good rumor or two about these tires. I think I am going to give them a try for my next set.

You would not really benefit from a track compound tire. They take time to come up to temp before they start working.

 

From looking through your NAM gallery I can see that you speak from experience (V700s stacked in your back seat). Where do you attatch your cam strap? I will likely transport tires in a similar manner as I do not like the idea of travelling to and from events with the seat folded down and a carload of heavy unrestrained objects.

Thanks for the feedback.

 

D-rings. You should be able find them in any hardware store. They attach to the child seat anchors.

 

I ran the first 2 events this year in the R56 on the Azenis left over from the R53, and thought wow I love this new car. I mounted Kuhmo V710's (16" already had slipstreams) for the rest of the events this year and I really love the new car.

Yesterday was a test and tune and with the expectation of 40-50 40 second runs I decided to run the street tires. 205/55/16 Direzza Z1's wow is all I can say much better than the Azenis. I do have to say that the majority of my experience with the Azenis was autoxing in my 04 MCS so some of the difference is car, but I run the Dirreza's as my summer set up on stock 16" rims and I like the daily driving characteristics too. They seem to be wearing pretty evenly with the slight rounding of the edges.

I think on the R56 the 17" setup on most courses will be the faster setup.

Jody

 

What PSI are you running in the V710s? 215/40/16.

 

42 front, 46 rear or there abouts depending on how much rotation you need.

 

A new tire size for 17x7 rims in Kumho V710

are 215/40-17 which should be fine for G stock class.

If you need street tires for longer treadlife and lower cost then
Dunlop Direzza Z1 Star Spec in 215/40-17 is a good choice.

For beginners usually it is better to use street tires when starting out-
Gain experience first plus the tires will wear longer and can be used for street driving. There would be no need to change wheels at the event.

Using R compounds would help with grip and lower run times by about 1 to 2 seconds per 30 to 45 second lap depending on your skill level. But the tires are expensive and tend not to wear well beyond about 6 to 12 months of use and sometimes less. Heat cycles and time will harder the rubber and decrease performance.

Some R compound tires are better suited for longer courses or dual drivers where heat build up is of greater concern. Then the Hoosier R6 or Toyo Ra1 might be more useful.

On a short 30 to 40 second course often the outside of the treads heat up without the rest of the tire warming up.

To find out what tire pressure is best for your suspension setup and driving style you'll need to chaulk your sidewalls and check tire temperature with a pyrometer as soon as you finish your run. If the middle tread temperature is highest you can let our some pressure, if it is the lowest then add pressure. Right and left side tire temperatures can vary so it won't all be perfect but you want some inner and mid or outer and mid temps to be close.

Typically without -2.0 degrees negative front camber you will be hottest on the outside treads in front where the tire is working extra hard on cornering.

 

I don't think there are too many GS MINIs with -2.0 degrees front camber.

 

My R53 has -.4
I believe the R56 can get about -1.0 if you remove the alignment pins from the strut towers.

 

That is not what I meant.

Stock new R56 MINIs can expect to max out at about -1.0 degrees which is better than -0.5 that most will have from the factory.

Don't expect your tires to do their best until you can reach about -2.0 to -2.4 degrees for front camber.

So my point is with -1.0 degrees you do get some benefit, just not the best benefit from your tires- not matter if street or R compound.

Expect faster wear on your tires as a result. Less performance, more wear- that's the cost of less front negative camber whenever you do performance driving whether on the track, at driving school or at autocross.