Interesting tire degradation with BFG R1 S

[Pat]

Yesterday I was at the local track for the first time this year. It was the second day I was on BFG R1-Ses. Both days I've had trouble preventing the tires from graining. Here are the stats on my setup for each day:

Day 1 (last October):
2.6* front camber (no toe)
35-36 psi hot all around

Day 2 (yesterday):
3.2* front camber (.1* toe in)
34 psi hot all around

Graining yesterday was not as bad as it was the first day with them. That said, it was still an issue even though ambient temps were in the upper 50s. I'm surprised I'm still seeing graining. Take a look at the pictures and you'll see an area near one of the radial grooves in the tire which appears to have been worn more than the rest of the tire. Should I really drop pressures down to 32ish? Less than 34 seems pretty minimal for this setup (225/45-17).
I remember last year when I posted about this someone suggested I run something like 28 psi hot, but unfortunately my sessions were cut short yesterday dealing with personnel issues so I didn't really get a chance to play with pressures much.
Temperatures were fairly even across the tire as measured with my China Freight IR pyrometer, with the inner shoulders being about 15* higher on average.









None of this really makes sense to me. I think I have a good alignment. Tire temps seem reasonable. But the inner shoulder is a little hotter and it looks like it isn't wearing as much. Do you guys have any ideas what is going on?
The good news is I improved my best lap time by half a second and I know I can go at least another half second faster. Maybe even a whole second. The car feels really good before the tires grain.

[CSG Mike]

Do you have pyrometer readings?

[TrqlessWonder]

That looks like both graining and OPR.

Toe-in up front? Why?

Take with a grain of salt, as I stick to autocross (and stock/street, no less), but I've run 4 different tires from an A6 to the primacies on the car and they all seem to vastly prefer being in the 30-32f and 28-31r range for me. So...the lower pressure advice doesn't strike me as a bad idea. And use bigger test steps than half-psi at a time.

[renfield90]

Originally Posted by TrqlessWonder

That looks like both graining and OPR.

Toe-in up front? Why?

+1, that's graining. Given ambient temps at 50 that's not a surprise IMO. I will guess the toe in was because he's lazy like me and ramped up camber to max without adjusting toe.

You have less graining now than in October because they've already been through a heat cycle.

FWIW I run something like 30-32psi front and 29psi on the BFG Rival S. No guarantee that those pressures will translate to your tire of course, but it's proof that lower pressures aren't necessarily a bad idea.

If temperatures are even though, I'm not really sure you need to make any further adjustments; just keep adding heat cycles or wait for warmer weather and the graining should resolve itself. It probably took 10 heat cycles or so for my Rival S to quit graining, but to be honest I felt maximum grip was available when the stickers were still on.

[Pat]

Originally Posted by TrqlessWonder

Toe-in up front? Why?

I aligned the car to have zero toe for daily driving. The downside of it is that it creates a tiny bit of toe in when I increase camber at the track. It's a known compromise.

[Pat]

Originally Posted by CSG Mike

Do you have pyrometer readings?

Unfortunately not this time.
I'll be at the track both days this weekend. Maybe I can measure more there. But it's supposed to be in the 40s and raining. Meh.

[philooo]

FYI BFG recommend much higher pressure on these tires, check this PDF on terrace website, for car around 3000lbs, BFG recommend 36/42 hot.

I run BFG R1, and I run them around 38/40 hot, and the wear and tear is much better than at lower temperature.

[e1_griego]

Yeah, I tried higher pressures and for my car it was awful. Mid 30s psi was bad bad bad.

I got more than ~85 autox runs from my first set of r1-s with great wear (minus the flatspots) and clearly they tire was happy (or at least wasn't unhappy). I actually still have that set and they have tread still but they've heat cycled out. I use them for practice/ fun-run weekends.

[Pat]

Originally Posted by philooo

FYI BFG recommend much higher pressure on these tires, check this PDF on terrace website, for car around 3000lbs, BFG recommend 36/42 hot.

I run BFG R1, and I run them around 38/40 hot, and the wear and tear is much better than at lower temperature.

Thanks, philoo. I have seen the BRG recommendations. I tried higher pressures last year and they seemed to get worse.
Let's assume I should run higher pressures. How would one explain the extra wear on the tire near one of the radial grooves? Wouldn't more air just make that even worse?

[TrqlessWonder]

Originally Posted by Pat

How would one explain the extra wear on the tire near one of the radial grooves? Wouldn't more air just make that even worse?

A) When you lean the car over hard in a turn, those grooves are presenting nice little square edges for the track surface to try and tear away at. And hey, the tires are being mercilessly pressed against that surface from the car side, too! It's the corners/edges of the grooves being opened up by turning.

B) It would certainly make it look worse, but you'd eventually inflate to the point that the grooves never contact the surface, and then you just cord the tires away (probably quickly) at the center rib.

Be mindful that you don't take those manufacturer manuals as Gospel. 7 pages with lots of marketing photos probably isn't going to cover every car for every situation. "80% of the time, it works every time." It's a starting point.

[renfield90]

Originally Posted by philooo

FYI BFG recommend much higher pressure on these tires, check this PDF on terrace website, for car around 3000lbs, BFG recommend 36/42 hot.

I run BFG R1, and I run them around 38/40 hot, and the wear and tear is much better than at lower temperature.

From that link:

Heat Cycling
Heat cycling can benefit the BFGoodrich g-Force R1 by helping it perform more consistently over periods of constant extended use. In addition, on-track heat cycling adds texture to the smooth surface of your new R compound tires. The process is painless. Simply run a few laps to get the tire up to operating temperature (160°F-220°F) and pressure, then allow the tires to sit off the car for 24 hours. That’s it.

That is pretty damn hot. Are you sure you're getting your tire up that high on a 50 degree day? Pat, that's probably why you're graining right there.

[Pat]

I don't remember exactly what I saw for temps last weekend. I just remember they were all pretty similar other than the inner shoulder being a bit hotter than the rest. I'll be out both days this weekend, take good measurements and post them here. The forecast is for 45 degrees and rain, unfortunately.

[Pat]

Well, so much for following up on this post with data from this weekend. We're supposed to get 18" of snow. I guess I'll just go ski and update this after the next track weekend at the end of May.

[Pat]

Last weekend I experimented with significantly lower pressures. I am not yet confident in this, but believe the sweet spot for the R1S on stock suspension with 3.2* of front camber is about 29 psi. Here are the data:



Unfortunately I didn't get time to measure temps at 29 psi, as there was a lot going on.
The more I experiment the more I learn. I'm starting to think this tire would just be a great autocross or time attack tire, and not so good for extended lapping, even on a lighter car. When I started at 24 psi cold, it took two to three laps for them to come in, as expected. Then I would get maybe three laps of really good grip. But after that they would start to go away noticeably. They just seem to give up once they get hot. It's really a frustrating experience. Although not as frustrating when they are at 29 hot compared to 35 hot, that's for sure.
I think I'd be significantly happier with the R1. I just don't think the S version is well suited to extended lapping sessions. What do you guys think of that?