I have a 2005 MCS JCW with 10 month old Bridgestone Potenza RE11 215 45 17's with about 400 miles on them, most of which has been 5 solo events and 3 track days (and driving to and from). I have not rotated the tires, and perhaps I should have done so earlier.

For solo I run air pressures hot of 40 front, 50 rear. This is the recommendation of local Mini solo veterans. For track I run 45 front, 40 rear.

Yesterday at the track I noticed the right front (passenger) tire was blistering, so I cut my day short. This hadn't occurred before and I believe I was running about the same tire pressures earlier (perhaps a bit lower). The only other differences were I had an instructor (so 175 lbs more) and I installed a strut tower brace last week.

The damage on the outside edge doesn't appear to be clearance related as I see no evidence of rubbing on the fender. Plus this would not explain the rest of the wear.

So what is the verdict on the tires? Replace? Okay as rears?

And what changes should I make? Rotate more often? Different tire pressures? Adjust the camber?

Thanks,

Deven

 

Here is a photo of the rear tire for comparison.

 

well for one thing by increasing the pressure you reduce the amount of tire contacting the ground. it's probably wearing where it's meeting the ground. no more input from me other than that observation

 

That's not that abnormal...

Rotate the tires and run them till they cord.

You should get another set of wheels and tires to bring with you to the track, and more negative camber at the front. I run -2.8 at the front which gives good wear.

Try the Kuhmo XS next time. I've had good luck with them.

 

Looks like full tread tires getting hot to me... common at track days to see something like this. Depending on where you're running you can also pick up opr (other peoples rubber) although its not usually an issue at track days.

 

Any concerns about continuing to use the tire as a rear?

 

Nope

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Seems to me you are running too much pressure.

 

What would you suggest for track?

 

For the track (not for autocross), I'd start off 36-38 front and 32-34 rear. As the tires heat up the pressure will build to around 40ish front and 38ish rear (I like a little less pressure in the rear). Then you can play with the pressures. You might even want to pull in after 5 or so hot laps just to see where they are and adjust. It's not like during autocross where you don't have enough time for your tires to heat up so you want to go with the higher pressure in that instance, but on the track, after a few laps, your pressures should be close to where you want. Make adjustments prior to the next heat after they cool down.

I'm by no means an expert, but this is what I've been taught at the track, and so far, it's worked out pretty good.

 

We usually see the pressures increase more than that. Something like 6-8 psi with Z2 star specs

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Your tires were overinflated as discussed above. You should try to rotate front to back between each event. Sometimes I do that in the middle of a track day.

 

I'm sure you are correct, but if the wear triangles on the edge of the tire are gone, doesn't that indicate that the tire is rolling over and needs more air?

 

Yeah, I have seen them go up that much as well. A lot of factors involved. Tires, track temps, etc. I think the key is to experiment and come off the track during a session to find out where they are and adjust.

 

Tire pressures can be used to change the balance of the car. I use 34 psi front and 44 psi rear. Helps the car turn.

Dial it in based on the how the car feels. Spring rates, sway bar settings, and shock settings also play a role.

 

Are these for track or solo?

 

track

 

I think that your tire wear is to be expected given your stock alignment and use of street tires for track.

If you want better tread wear on ANY tire you will need more front negative camber, plan on adjustable front camber plates. Talk to Way at Waymotorworks to get more info.

Without the negative camber in front you will wear out the outer tread edges very fast or in your case heat up the tread very fast which can lead to tread "chunking", a loss or chunks of tread blocks, not blistering. In addition, due to lack of camber your tread on the inner side blocks are relatively spared.

If you bring a tire pyrometer (probe type) to the track and go out for a session (10 laps will do nicely) as soon as you pull into the pit area check the tire temps especially on the fronts and you will see if the tire temps are close or way too hot on the outer edges. If you make lots of high speed left turns your right front outer tread edges will be smoking hot and prone to wear.

Using a R compound tire built to be more durable for track use is key for better tire wear unless you like burning through street tires in a few days. The investment is well spent and some track tires are easily streetable. Toyo R888 is a common choice.

These days you can also consider Extreme Summer tires more recent than the Bridgestone RE-11, like the BF Goodrich Rival. Again, without more front negative camber it's going to be tough to use the tire evenly.

The rear tire could be used for more events but do check your tires for wear often as they can cord at some point with track use.

Tire pressures may vary from MINI to MINI and from driver to driver. Start somewhere and see how it feels to you and chalk the tires to check for rollover on the tread shoulder as well as check the tire temps. Adjust pressures as best you can to make the best use of your tires, keep the temperatures as even from outer to inner treads, it's not easy even with more negative camber. Tire pressures do not need to be the same on each axle, the tires that are the hottest can have slightly higher pressures to help use more of the middle tread.

Finally, get some instruction at the track, one of the things to learn is how to drive well and keep your tires in their "happy place". This means driving smart and keeping under control to conserve your tires (and brakes). Turning at speeds too fast and braking too hard or too late are common errors that will generate excess heat. Be patient and respect the slower parts of the track.

 

Minihune,

Thanks! Very useful.

Deven