Common wisdom - track wheels and tires

[D-O]

Anyone try 18x10 ET25 square? I am told it will work with -3.5 front.

[bigjae46]

Thanks.

Is this more an issue of chasing absolute grip, rather than optimizing tire size for the rim? Does the increased heat tolerance of a physically larger tire figure in?

Trying to learn as much as possible before dropping a bunch of money on track wheels and tires.

It is about maximizing the contact patch so yet...grip. A wider tire on a wider rim should result in a larger contact patch, not sure it would affect heat tolerance.

If you are talking about the outer diameter, that affects tire temps. A smaller diameter tire sees more revolution at a given speed which generates more heat. Also changes the final gearing.

[D-O]

You'll be fine. I've done it before with 17" wheels

Thanks.

Is this more an issue of chasing absolute grip, rather than optimizing tire size for the rim? Does the increased heat tolerance of a physically larger tire figure in?

Trying to learn as much as possible before dropping a bunch of money on track wheels and tires.

[bigjae46]

Question for the folks running 275 width NT01's on a 9.5" rim. According to Nitto, the tread width of the 275 in both 17 and 18 inch is 10.6". Are you guys having any issues with this rolling under? 10.6" seems too wide for a 9.5" rim.

You'll be fine. I've done it before with 17" wheels

[D-O]

Question for the folks running 275 width NT01's on a 9.5" rim. According to Nitto, the tread width of the 275 in both 17 and 18 inch is 10.6". Are you guys having any issues with this rolling under? 10.6" seems too wide for a 9.5" rim.

[OldRanger]

What PSI are you running?

27 psi cold (or prior to a session start) with psi somewhere around 35 psi when coming off the track.

And does the shop do a string alignment or a laser alignment.

I don't know. I have chosen a nearby race shop (RRT Racing) based on reputation and familiarity with the E46.

Could also be a bushing issue. Rotating tires makes it more difficult to pinpoint the problem. A spherical RTAB significantly improved my tire wear over a relatively young OEM RTAB with limiters.

That's interesting. I have relatively young OEM RTAB with limiters and OEM FCABs. Although I didn't think about this as a contributing factor to tire wear, it converges with the only recommendation I got on car setup from a very experienced driver that drove mine for a session. His thought was "setup is awesome, maybe a bit more front camber and delrin bushings".

Also from last weekend: Estoril let me borrow his contact pyrometer to take temps and the inside-center-outside temperature range was fairly tight. < 10 degrees variance from 12 different measurements when I drove and <5 degrees variance and 5 degrees lower when the more experienced instructor was in my car.

My conclusion from looking at other RE71RS users is that this wear pattern is common, even on instructor's cars. I'm not the only one that hasn't figured out a way to prevent it.

[OldRanger]

This thread might help - https://www.m3post.com/forums/showthread.php?t=1607489

There's a lot in there - thanks for the link!

[bigjae46]

The tires wear that way in front and rear posiition.

OK, maybe it's not abnormal. But I'm surprised by the odd wear pattern on the outer edge of the center tread. If I had to guess, that will be the first place on the tire that will be completely worn out.

Maybe that tread block should be more rigid than it is for track use? If it is user error due to tire pressure or alignment, then I'm surprised (but willing to learn). I take careful psi measurements after every session and I have a reputable race-shop-performed alignment.

What PSI are you running? And does the shop do a string alignment or a laser alignment. Laser alignments are much faster but not always as precise than a string alignment. There is an art to it and even then even the BMW specified Hunter alignment rack will not be 100% repeatable.

Wear is an indication of excessive heat. That kind of looks like toe wear but also could be camber wear.

I run -3.8 F and -3.0 camber front and rear and target hot PSI is 30 hot, I'm OK with as low as 28. Cold target is 6 psi lower in the morning which gets me to about 28psi hot for the first session. I get even wear across the face of the tire. My car is also 2825-2875 with fuel and driver. Sounds like your car is heavier, might need to add more negative camber front and rear, probably more than me because your car is heavier. Then toe settings become more critical for wear. Really need to be at zero on the front axle. I target half the toe as the stock spec on the rear.

A starting point for most tires is psi every 100 lbs as driven. So a stock car with driver and fuel is around 36-38psi hot.

Could also be a bushing issue. Rotating tires makes it more difficult to pinpoint the problem. A spherical RTAB significantly improved my tire wear over a relatively young OEM RTAB with limiters.

[Slideways]

The tires wear that way in front and rear posiition.

OK, maybe it's not abnormal. But I'm surprised by the odd wear pattern on the outer edge of the center tread. If I had to guess, that will be the first place on the tire that will be completely worn out.

Maybe that tread block should be more rigid than it is for track use? If it is user error due to tire pressure or alignment, then I'm surprised (but willing to learn). I take careful psi measurements after every session and I have a reputable race-shop-performed alignment.

Can't say that this is an alignment issue. My guess would be PSI, tread design or tire compound. Tires look like they are at the wear bars, so that center wear seems like it would be acceptable.

This thread might help - https://www.m3post.com/forums/showthread.php?t=1607489

[OldRanger]

Front or rear tire?

Either way, that isn't abnormal.

The tires wear that way in front and rear posiition.

OK, maybe it's not abnormal. But I'm surprised by the odd wear pattern on the outer edge of the center tread. If I had to guess, that will be the first place on the tire that will be completely worn out.

Maybe that tread block should be more rigid than it is for track use? If it is user error due to tire pressure or alignment, then I'm surprised (but willing to learn). I take careful psi measurements after every session and I have a reputable race-shop-performed alignment.

[bigjae46]

I don’t like the way the 265 RE71 RS is wearing.

I’ve been rotating and adjusting pressures a couple PSI but I’m still getting irregular wear

Front or rear tire?

Either way, that isn't abnormal.

[Tbonem3]

My 18x9.5" ARC8s in ET35 require at least 5mm spacers to clear the 996 brakes with Rally Road brackets at the spokes, but at that point you need a hub extender or spacer with one built-in to stay hubcentric. It's annoying.

Same situation here, but the 5mm still leaves enough hub lip if you have aftermarket wheels with a smaller inside bore chamfer. Stock wheels' chamfer is larger and you gotta go to 3mm.

[heinzboehmer]

I don’t like the way the 265 RE71 RS is wearing.

I’ve been rotating and adjusting pressures a couple PSI but I’m still getting irregular wear

Mine are doing the exact same thing. Doesn't seem to affect driving much... yet

[OldRanger]

I don’t like the way the 265 RE71 RS is wearing.

I’ve been rotating and adjusting pressures a couple PSI but I’m still getting irregular wear

[D-O]

It will gear up the car a little bit. The downside is a smaller outer diameter tire can start to overheat if you're running at a high speed track like COTA or Road America which will accelerate wear and likely have less overall grip.

But a 255/40R17 it probably right on the edge, should be OK. I tried a 245/40R17 and it was too small.

Thanks.

Heinz - Ah. I get it.