Hi all - I have settled (like many of us) on Enkei RPF1s for my street legal but gutted track-dedicated 2005 Mini Cooper S R53.

My main concerns are:

1. Tire availability
2. Fitment
3. Weight
4. Balancing grip vs rolling resistance and added weight of wider tire



I am trying to keep the weight down so I am pretty sure I want a 16in wheel but am open to all suggestions from track rats.

 

I can tell you that the IMSA Continental Tire Sportscar Challenge all use 17 inch tires (that is the size Continental supplies). And TUDOR United SportsCar Championship runs exclusively on Continental’s ExtremeContact™ DR (Dry Race) tires.

So 17 inch Enkei RPF1 are as light as Weight: 14.6 lbs. maybe matched up with some PIRELLI, P ZERO TROFEO, Streetable Track & Competition, Size: 205/45ZR17 (88Y) XL
or if you want something that is a little more streetable and better in the wet there is the CONTINENTAL, CONTISPORTCONTACT 3, Max Performance Summer, Size: 205/45R17 84V

EDIT: Since you mention it was streetable, I figured you were driving it to the track... and these are the 7 inch wide rims. And as a track car I assumed you are going with a Big Brake Kit, with possible cooling ducts and vents.

But I really have to say it all depends on the depth of your wallet...

Motor on!

 

Do not want a more streetable tire ... notice the post says track-dedicated

 

I actually ran 15" wheels on our track R50, primarily for weight and low cost of tire. You will probably have to run 16s if you're trying to stay legal in a 'stock' class with a R53.

 

Since this is a track toy, what do you have planned for a brake upgrade? If going to larger brake rotors, that might dictate the wheel diameter. For example, I upgraded to 13" rotors on my 2003 R53 and that required a 17" wheel to clear the rotor/caliper.

 

Yes I will be going to the Wilwood big brake kit 12.2 supposedly fits most 16in wheels. Unless AP racing offers somethign better but I need to look into that.

What width do you run on your 17s ?

I am kind of between a 16 x 7 or 16 x 8 right now

 

Thank you for the color.

The stock rims are 17s so I would imagine 16 or 17 will be fine.

Right now I am trying to figure out what offset and spacers might be involves to get a 16 x 8 to fit.

 

Appreciate the insight. Do you know what widths they are running ?

 

We run Enkei RPF1's on our MINI in 17's. 205/45ZR17. The tire on them though I wouldn't recommend for a track dedicated tire. Look into Dunlop Direzza ZII Star Spec. Love mine and a lot of great reviews. I also run Nitto NT05's. With the wheel size you go, I usually try to fit the meatiest tire recommended within spec so I have more rubber to put down on the track. The smaller the rim size on the wheel, the cheaper the tire so do keep that in mind.

 

Really appreciate the info and sexy pic. What wheel width are you running ?

 

My pleasure. So, I believe the wheels are 17x8. I know we are running 10mm spacers all around and had to put on Subaru WRX wheel adapters due to a fitment issue with the bbk. It was a lot of trial and error. You may need to do your research if you plan on running these wheels with a bbk. I'm not the person who knows exactly what the process took, but what I can offer you is to shoot Jared, the guy who built the car, an email at RSVP9146@gmail.com as he said he'd be more than willing to go over it with you to help you out. Added a few more snaps so you can get a better side profile view of the stance.

 

I used BBS RGR 17x7 ET38 wheels with 15mm spacers on my 2003 R53 with the 13" wilwood rotors and 4-piston FSL calipers. I used 215/40-17 tires.
If 16 wheel can fit over your brakes, I would go with 225/45 tire because the Dizezza ZII Start Spec is available in that size. There is a better selection of tires if you jump up to 17" wheels.

 

Great I appreciate the help man!

 

I can get the ZII in 16 x 8 i was t old

 

No problem, glad I could help!

 

The 2 wheel diameters with the best tire selection are 15" and 17". These two wheel sizes are used in the BMW E30s and Spec Miatas for the 15" and the racing noted above for the 17". A check on Tire Rack will show you that the 16" falls behind these 2 wheel sizes for selection.

You didn't mention if you were trailering this track car. I know you said street legal but I have seen a lot of street legal car that are trailered to the track. If you are trailering there are several really good track tires to consider...the Toyo R888s & RA1s and the Nitto NT01s. If you are going to drive to the track then the Dunlop ZIIs and Bridgestone RE71Rs are probably your top choices.

Don't bother with max performance tires...Look at post 48 to see what happens to these:
https://www.northamericanmotoring.co...estions-2.html

In comparison to those tires, my ZIIs are still in great shape after 2 or 3 times that track time.

For tire size, 205-50x15 215-45x17 or 225-45x15 or 17 should work. I have seen the 225-45x15s on 8" wide wheels with 35mm ET fit on a Gen I MINI. On a Gen II MINI, I run 225-45x17 on 7" wheels with 45mm ET. But I think this is a bit wide for a 100 wear rating tire on a 7" wheel; a 215-45 would be a better fit. The wheel fitment on the Gen I seems to be a little better than on a Gen II so you should be able to get away with the 8" wide wheel

The Wilwood 11.75/12.2" rotor BBK is a great option and if you go with the 11.75" rotor you can run 15" wheels which will lower the car by an 1 inch as compared to the 17" rims. I have run my Wilwoods in both formats and the 11.75" have plenty of stopping power for the track. I am currently running 17" wheels so I have stayed with the 12.2" rotors but I am looking into going with 15" wheels to lower the car and to further reduce the weight.

Hope this helps.

 

You are wanting to get into 15 inch wheels to lower cars center of gravity and reduce wheel weight. Are you aiming at autox performance or track performance?

With a 15inch wheel clear the stock brakes?

I am driving the car to the track so I agree with your tire recommendations for that configuration.

The wheel weights offered by 15in wheels along with the lower center of gravity are very attractive to me. What offset would you recommend?

 

subquestion ... and more importantly ... are the ZII or Bridgestones available for the 15x8 option without getting stretched

 

What exactly are your plans for the MINI on a track?

Competition track series, if so, how many events?
Track lapping sessions, 15-20 minutes per heat x how many heats/event?
High performance driving on a track- open events

How durable do you want the tires to be? The choice of tire will depend on it's use, do you need fast time attack like race times? Or maybe something with moderate grip but longer wearing so that you don't have to burn through tires after just a few times out.

Soft rubber grips well but wears very fast and it is common to burn through street or race tires alike depending on driver skill and suspension setup which are both key to tire longevity.

Essentially you want a good match between choice of track tire and what you need them to do and how long you want them to last.

Realize that soft race rubber tires will heat cycle and get hard with time so even if you do conserve your tires, they may loose grip at some point. For track duty the more common outcome for tires is that they cord, often faster than the owner would like.

The comments about what brake choice you make will affect your ability to use 15" and some 16" wheels. You need to think about and decide if a larger brake kit will work and as you mentioned you have a Wilwood in mind which is fine. In that case a 16" wheel is OK.

So to address some of your concerns:

1. tire availability- this can vary, new Extreme Summer tires are getting so good now, they are approaching the performance of durable Race tires and cost much less. Further they can be used on the street but often are noisy and might not be so good in the wet. They don't always come in sizes that are friendly for certain wheel sizes but you want to match the wheel width with the tire width for best fitment and best tire grip and wear in a harsh environment like a track. Bridgestone RE-71R is the best Extreme Summer tire out there, followed by BFG Rival S and Kumho V720 for now.

2. Fitment- you want a combination of wheel and tire that doesn't rub under track use but doesn't bottom out and doesn't need a wheel spacer unless you need it for brake caliper or suspension clearance. You can use an adjustable suspension (full coilovers, front adjustable camber plates, rear adjustable control arms) to make the wheels have enough room to work as long as tire diameter is about 24". It doesn't really matter if the wheels are wide and poke out a bit. More important is that the tire and the wheel closely match so that tire geometry under use is optimized and predictable, and this also helps with more even tire wear.

3. Weight- tire weight by itself is not as important as the tire tread design, construction, and materials including rubber compounds used. I would use a slightly heavier tire if it had a lot from grip or wore better in the spots that I was going to use it.

4. Balancing everything out- besides the ones you mentioned there are many more variables to factor in. Sidewall height and construction will determine how stiff a given tire size will be and affect handling and responsiveness in hard cornering. An XL load rating is a plus when you can get it in a street tire as the sidewall has extra material and is designed to take a larger load so it flexes less. A 40 series sidewall tire is going to feel more responsive than a 50 series sidewall tire if everything else is equal.

The width of the tire should be maxed out for a given wheel width. In general if you have an MCS with enough power, about 220 HP or more, you can run wider tires with little compromise. A 7" wheel with 205mm wide tire will work as well but during hard cornering you will have slightly less grip and a tad more risk for understeer. Rolling resistance of a 225 vs 205mm wide tire is not a large factor for track use as you get poor mpg no matter how you drive.

Smaller tire diameter (less than 24") will lower ride height and center of gravity but comes into play best (due to lowered gearing) with lower speeds such as in tight corners or at autocross or on a short track course. But for a long course track you would want to be close to the 24" tire diameter, too tall a tire will start to increase risk for rubbing and other fitment issues not to mention raising center of gravity.

Finally, there are many other mods to be done to a track car to make better use of the tires. A limited slip differential like a Quaife would be a good way to reduce wheel spin under low grip situations and makes the most of the FWD.

Aggressive alignment with front camber of -3 or more degrees if you take turns hard or at higher speeds and rear camber to work with the fronts, usually about 1 degree less negative. Corner balancing is very helpful in a track car where you can adjust ride height on each corner.

 

Do you know what size rotors you have on the stock brakes? If I remember right, the Gen I S and base Coopers had the same brakes and a 15" wheel will fit over those and will fit over the 11.75" Wilwood BBK. If you have the first Gen "JCW" brakes, you will need 16" wheels to clear them.

As for tires, minihune comments are really good, to which I will add the following:
Unless you plan to be racing, where tenths of a second count, you will likely see little difference between the 7" and 8" wide wheels. If you do a search you will find that at least one very competitive autocrosser is pulling over 1g on a set of 205-50x15 Bridgestones RE71R tires on a base MINI with the stock wheels. I would highly recommend staying with the 7" wide wheels and not trying to stretch tires; that is not going to work well on the track where you are pushing things to the limits.

If you go to an 8" wide wheel then you will be looking at a 225-45x17 or 225-50x16 tire both of which are going to add 2 - 3 pounds of weight per tire and possibly have clearance issues. Also these tires are about 25" in diameter which is ~2" larger than the 15" tires and they will cost a lot more.

But there are other brands that you could consider such as the Toyo R1Rs, which come in a wider variety of sizes.

Another big factor that will come into play is suspension geometry and whether your suspension geometry will support and make best use of the wider rim and tires. You may find that without significant changes, the wider tire and rim may be no quicker than the narrower setup. My Toyo R888s are barely faster than my Dunlop ZIIs; I don't have enough camber to make good use of the higher grip that the Toyo's have.

Sorry to say, but there is no right answer here; just a lot of choices. And trust me, we all agonize over this very subject on an almost daily basis...

Good luck with it all and let us know what you decide...

 

As for offset, something between 38 and 43 mm ET; at least that is what I have used with success with tires up to 215. The R888 225s rub with anything less than 45mm. But that is on a Gen II MINI which seems to have less clearance than the Gen Is.

 

appreciate it enormously - agonize is the correct word for sure

 

Mind if I ask how much track experience you have and what tracks you are planning to go to?

 

I had PM'ed him earlier and he has motorcycle track experience, one driver school and one track day. He lives in Houston TX area and is planning on one track day per month, roughly five 20 min sessions on a short course.

Track tires will be used to drive to and from the track.

 

Sign up for the BMW CCA HPDE @ TWS August 29 & 30. I'll be there helping out with the Race School also running that weekend, and driving my R53.