[medphysdave]

New front tires are on.

Front Target. 0 toe, camber is what it is.

Rear target. .2 - .3 total toe in. -1.8 to -2.0 for camber.

Seem about right? Hunter alignment machines seem to be good. Ask if they measure ride height. I received some advice to have BMW do the alignment because it's warrantied for a year. That was new to me, but they charge a lot, so I'm kinda self warrantied by going elsewhere. I'd be surprised if BMW deviated from factory specs.

[medphysdave]

I'm thinking about returning to the alignment shop that did my previous alignment. The shop and person gets dynamite reviews for alignment. I think if I go in with some specs to target and let him see the pictures of my tires from my track day he'll likely put me on point. Or do I go for modern technology and try some place new? I did improve my PB by over 2s. Just wondering if alignment had something to do with it. I still say there was something wrong with these tires. Rears are super evenly worn. I'm impressed with how the rears held up.

I've run this tire on track previously. Last set did not experience anything like this.

Yes tires were up to temp. Brought them up with slow laps and long braking. Slowly bled down the pressure. These tires like between 36 -38 psi. Track Connect recommends between 36 and 41 psi. Hottest tire temp was 186.

This is the second set of cup2s at 3000mi and one previous track day.

[cme]

For one not enough camber. You need -2.5 at a min to avoid what’s happening. Pressures seem ok.
Chet

[medphysdave]

Originally Posted by cme

For one not enough camber. You need -2.5 at a min to avoid what’s happening. Pressures seem ok.
Chet

I agree. Definitely need more camber. I will say that on my last set I didn't get this kind of wear. However, the tires were much more worn by the time they had a track day. Maybe less rubber to chunk up. For comparison. Here are pics from 1st set of cup2s connects at 17k miles after track day right before replacement.

[medphysdave]

Here is the first track day on the set in the first post (2nd set of tires, brand new). Same alignment.

[cme]

Hate to say it but it’s the car. I have the same issue and am running -2.5 upfront with plates. Car is heavy. Also will note that one thing that the BMW Star 240 tires are more like 4s’s than Cup 2’s. I am going to switch to the Mercedes M0 markings on next set.

[medphysdave]

I've got a set of rt660s for next go around. I'm just surprised by the stark difference in how the fronts held up during this event. Maybe my confidence with the car was elevated with new pads so I was simply over driving the tires.

What does the M0 designate?

[cme]

Check out Tire Rack. M0 is tire spec for Mercedes. These are rated 180 vs the BMW Star which are rated 240 (same as 4S). The M0 tires are more track tires vs the BMW ones, which seem more suited for aggressive street driving.

[medphysdave]

Originally Posted by cme

Check out Tire Rack. M0 is tire spec for Mercedes. These are rated 180 vs the BMW Star which are rated 240 (same as 4S). The M0 tires are more track tires vs the BMW ones, which seem more suited for aggressive street driving.

Costco has them as well. Good price and $150 off a set of 4 right now. 255 sizes are cheap. I don't think they have the 275 though.

[sdhotwn]

To me it looks like the tires got too hot and were pushed past their limit. With the higher tread depth it's easier to create the higher heat in the tread and create delam - not unusual to shave a tire to prevent this if you are running it hard on a more "street" tire. More camber would have helped, but still could have occurred. I'm guessing a combination of the surface, the temps, and how much you leaned on the nose of the car.

There are textures and color tones in the tires that are showing the high heat, including the balling on the edges (different than regular pickup). Also, the amount of eating into the shoulder is unusual - regardless of camber.

[medphysdave]

I've taken this as a sign to not pound on the cup2 240 anymore. I'll be moving on to a different tire. See how that goes and then move towards fixing the real issue if I can't find a tire to last under the abuse.

[AUSf22]

Originally Posted by medphysdave

I've taken this as a sign to not pound on the cup2 240 anymore. I'll be moving on to a different tire. See how that goes and then move towards fixing the real issue if I can't find a tire to last under the abuse.

Agreed, cup2s don't seem to last with track use regardless of the treadwear rating. Proper semis like re71rs or the falkens available to you guys have much better wear and a stronger sidewalls which seem more fit for purpose.

And of course as stated above, more negative camber is absolutely crucial for even wear. I'm personally running -3.5 front

[cme]

I have been driving on 180TW Cup 2’s on my GT3’s for years. It’s not the tires. There is too much weight up front for the track and those tires are going to get abused by an experienced driver. Agree the 240 Star spec are not a good track tire. Also agree that shaving tires would help. Have to counter lack of camber and heat being generated by the front of the car.
Chet

[medphysdave]

Thanks. And you bring up a good point about the shaved tires. Certainly explains why the first set had no issues. The second set did have a good track on them when brand new, but track temps were much warmer.

The tire sensors on this day showed the tires were up to temp, but it was oddly cool at 55 degrees so the actual track surface temp was chilly. I wonder if that temp difference was keeping the tread cooler than expected.

2s a lap is still a big difference, so I was certainly pushing much harder on the day I nuked the tires.

[bdogk]

I'm looking at moving onto a wider front tire. No matter what, I find the 245/35's just too narrow. Has anyone tried 265/30's on stock or 9.5in rims for fit? I know there's limited brand availability on this size. For rears, I would try run 295/30's. Again, limited availability by brand/size.

[aroundelway]

265 fits if you run more camber 285 can fit but will rub without some work.

I went square 285 supercup 3r back to 265/285 it’s a great setup.

The car above needs more camber not different tires. Those are overdriven tires with too little camber.

[medphysdave]

Originally Posted by aroundelway

265 fits if you run more camber 285 can fit but will rub without some work.

I went square 285 supercup 3r back to 265/285 it’s a great setup.

The car above needs more camber not different tires. Those are overdriven tires with too little camber.

Do we think this same thing will happen with the RT660s if I don't get some camber plates? I was hoping to avoid camber plates until I decided if I wanted to upgrade the entire suspension, but if I'm going to destroy tires like this, then camber plates are a low cost bandaid.

What do I need to add to get more rear camber, or is stock reasonable?

[AUSf22]

Originally Posted by medphysdave

Do we think this same thing will happen with the RT660s if I don't get some camber plates? I was hoping to avoid camber plates until I decided if I wanted to upgrade the entire suspension, but if I'm going to destroy tires like this, then camber plates are a low cost bandaid.

What do I need to add to get more rear camber, or is stock reasonable?

Yes, you definitely need camber up front or your tyres will constantly wear on the outside edge/shoulder. If you plan to do a lot more track driving then I think this mod is mandatory as it'll not only give you better tyre wear but much better cornering as you have a larger contact patch on the road during lateral movement.

The rear camber is adjustable up to -2.1 to -2.2 without any modifications. Mine is maxed at -2.1 with only coilovers on the rear.

[medphysdave]

Car is in the shop today for alignment. I took my desired specs. He said -2 in rear should be no problem.

Front 0 toe, ~7.3 caster
Rear: -2 camber, .20 total toe

Hoping he can give me the front camber numbers even though they aren't adjustable. This is like old school by hand alignment. I'm not sure there is a digital tool involved.

[ZL9M2]

The issue is not enough camber in front. I ran into this issue on my '17. I wanted to run less pressure in the fronts to put the tire in its sweet spot, but could not as then I had too much wear and also overheated the outside edge of the tire. I now run camber plates set to 2.5 deg neg and can run the proper pressures with even wear and temps across the full tire tread.

[medphysdave]

Originally Posted by ZL9M2

The issue is not enough camber in front. I ran into this issue on my '17. I wanted to run less pressure in the fronts to put the tire in its sweet spot, but could not as then I had too much wear and also overheated the outside edge of the tire. I now run camber plates set to 2.5 deg neg and can run the proper pressures with even wear and temps across the full tire tread.

This sounds like me. Track connect sensors are great, but they are in the center of the tread and not the edge.

[bdogk]

Originally Posted by ZL9M2

The issue is not enough camber in front. I ran into this issue on my '17. I wanted to run less pressure in the fronts to put the tire in its sweet spot, but could not as then I had too much wear and also overheated the outside edge of the tire. I now run camber plates set to 2.5 deg neg and can run the proper pressures with even wear and temps across the full tire tread.

My vorshlag camber plates are going on. I'll be setting them to -2.5 fr and -18. re. What fr/re pressures do you run?