Why RE-71R's torn up after one event?
 

Hey y'all, appreciate any input here. This is my first time posting, though I've been reading for years. I was so excited to get my new RE-71R's for my birthday. I put them on a second set of wheels just for autocross so I could make them last longer. This is my first significant jump into "performance level" autocross.

But to my dismay, after one event one of the tires got torn up pretty bad. This can't be normal can it? It's worn down the middle section like this:

Attachment 181365

Attachment 181366


You can see how uneven it is. That edge is worn down about halfway already compared to the rest of the tire.

The other three tires aren't as bad. They look like this:

Attachment 181364


So weird how it only happened to one tire, and only down the middle. Like I said, any input would be appreciated, any experiences you can share. I'm just trying to figure out how to avoid this in the future.

thanks


More details below:

- I used chalk on the sidewalls to monitor pressure; I ended up letting a couple pounds out of the front and more out of the back during the course of the event. The chalk method always worked well for me with previous tires (the stock tires, then the Indy 500s). Using that method, I normally end up doing the same thing, taking more pressure out of the rears than the fronts. So I'm not sure what went wrong this time. The fronts did wear down below the triangle indicator more than usual, but I didn't think it was that bad so I didn't pump any more air in during the event.

- I sprayed water on them after a few runs, which I had never bothered with before. This was on a very hot Georgia day, with 8 one minute laps. At one point, a friend touched my tires and said they were really hot. That's why I sprayed them after a few runs, and did it every time after that until the last lap.

- Unfortunately, no, I don't know if these were on the front or rear (there's a longer story behind that)

- Even though I didn't put them on until I got to the event, I left them on for 5 days after (also part of the longer story). But I took it easy on purpose for those 5 days. Come to think of it, I didn't air them back up right after the event, I waited until I got home. That means I drove an hour on the highway at autocross pressures. But when I got home, I aired them back up to normal street pressure after waiting for them to cool down.

thanks again
:thanks:

Last time you did your alignment? What's the DOT code on the side of the tire? Maybe they were in storage for a while


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Normal wear, first 20-40 runs look awful but then they stabilize and are in it for the long haul. Between my dad and myself we've been through 7 sets of RE71Rs iirc. We typically see 130-140 quick runs out of them but in ST trim we've had over -3 degrees of camber, in Street I'd expect closer to 100 runs, maybe less on abrasive concrete, could be way more on smooth low wear asphalt.

Autox courses seem to end up clockwise or counter clockwise, the outside front tire for the most sweepers where you were pushing is likely the most worn. Turning and braking action accelerates the center rib wear, I usually chew up fronts harder than rears so every event the better tires go up front.

STX pressures with camber should be around 29psi hot, Street a little higher due to lack of camber and pinching the 225 onto the 7", I'd guess 32 psi or so.

They look okay. Alignment specs?

Also there's a good chance you were over-inflated. Anyone wanting to get into performance driving need need needs to get a quality pyrometer to monitor tire temps. You can tell so much from that.

As mentioned, normal wear for these tires.
I think the chalk method is better suited for bias ply tires, and those little arrows just point to where the treadwear indicators are, i don't think they are intended to be used to set pressures. Just aim for 34-36psi hot...

Overinflated the hell out of that tire. Also, ideal tire pressures vary with tire size (diameter). You can get away with a lot lower pressures on a tire that is wide enough. I cringe everytime I see guys running 36-38psi on 255 tires. People will always defend those high pressures saying that the sidewalls roll over at lower pressures, which might be right, but its a problem of using a tire that is too wide for the wheels you have, not a problem of pressure.

So with all of this, my question is, what were your tire pressures, specifically that one tire, and what is your tire and wheel size (width)?

I do know that wider tires have higher volume and to carry/support same load/car mass need less pressure vs narrower ones. But what is formula given new and old tire sizes and pressure for old, to calculate supposed pressure for new wider tires?

The chalk method is not going to tell you anything worth while. The wear you are seeing indicates they were over inflated, order a cheap pyrometer on Amazon and collect some data to set the pressures properly.

Agree with the others saying it's normal, though that first photo does look nasty. I remember I had the same experience with mine in autocross the first time I tried the RE71Rs. They wear SO quickly at first, and that's the result, but they will settle and look more normal after awhile.

Also, as far as pressures, not sure what size you're running, or what your camber settings are at, but I run 245/40R17 RE71Rs, and I compete at 26 PSI front and 27 PSI rear. My camber is -2.5F/-2.0R.

As low as you can run them without the sidewall rolling over and still getting them to ideal temperature, thats the formula. You need a sensible butt dyno to feel the tire rolling over and a pyrometer to measure temp. For autocross you may need higher pressures just because the runs are so short you wont get them up to temp fast. On the track, temperature is rarely a problem (its usually the oposite, you have too much temp).

My butt dyno is very badly calibrated with readings widely fluctuating in very wide range :), hence would prefer quickly calculateable numbers at least for quick initial rough getting into ballpark.

Looks like relatively normal wear, with a little bit of over-inflation.

These are FAR stickier than the tires you've run before, and will generate more heat, and thus, more pressure.

Buy a pyrometer, and adjust alignment and pressure with the pyro's readings.

I don't agree with the "low as you can go" approach to tire pressures...
And anyway, there's no definite point of transition between "sidewall is not rolling over" to "sidewall is rolling over". Radial tires are very stable over a fairly broad range of pressures. Also this may be a recipe for running too much pressure for under-cambered cars, and too little pressure for cars with track-appropriate 3-4 degrees front camber.

For most of our cars, there's going to be a quite broad range of pressures that will perform well, IMO there's no reason to try to find the lower limit.

You can invest in a pyrometer and try your best to get actual representative hot temps, but then you still have to correlate that back to what is the best temp distribution across the tread for quickest times for your car.

Or you can just run 34-36psi hot pressures and not worry about it any further, for 99% of us that's going to be close e-damn-nough...

Stopwatch > pyrometer