I had an incident with a V710 during an AutoX this weekend, was curious if anyone else had experienced the same? late on the course I was very deep in a turn front passenger tire rolled off the rim 50lbs of air high 80's Don't appear to have any damage rims were MINI 16" 5 spoke R84s I think. No apparent tire damage I will try and get it re seated this week. Its possible the tire was slipping on the rim before hand I was told it looked funny the intire run. To bad I think I would have knocked off an excellent run felt like I was really moving.
any comments would be appreciated.
On the bright side I can now honestly say I have driven the tires off the car

 

50 psi ! !

That was your problem. Way to high on tire pressure. Shouldn't be more than maybe 40psi.

 

If you had 50 psi cold pressure you had more than that hot, that's your problem.

 

Don;t think the pressure was the issue Any other G-stockers out there with some comments

 

I routinely run upwards of 60psi in the rear, using Kumhos. Don't think pressure was the issue.

 

Just so you know I'm running below 40 psi. When I go above that, my times start to drop.

 

Why in the world would you run 60 psi in the rears?

 

Rotation would be my guess.

Scott
90SM

 

rotation baby rotation

 

But w/ the Hoosiers, the pressures can/should be a lot closer.

 

On the V710s I run 47-48 in the Front and 62-64 in the rear. So I don't think pressure was your problem either. I'd say if anything, the higher pressure would make it harder to pull off the rim, than too low pressure.

 

I believe I remember hearing that it is more difficult to mount the 710's on stock wheels than it is on the aftermarket wheels of the same size. Maybe something wasn't right to begin with? I would think it would have been visibly noticable from the start, though, so who knows.

 

The 215 sized v710's are tough to install on any rim in the 16x6.5. Believe me I know

Some guys have had enough practice that they don't even complain, but that's not the norm for most tire shops.

 

wow, 60psi. I had no idea where to start on pressures yesterday, which was our first day on the track. We ran 42/45 and I was complaining about the rotation thinking that my alignment must still be off. I still think my alignment isn't on yet, but i'll definitely bump the pressures!

d

 

Running that high of pressure is sure going to reduce the contact patch, not sure why you would do it........?

 

Only the pyrometer can confirm that or not. I'd like to see the tire temps of a 60psi tire across the contact patch.

d

 

At 60 psi I am sure it would look like a motorcycle rear tire tho......

 

The answer is still the same. Rotation.

Please note that Per said he uses 60psi in the rear.

He's not trying to maximize rear grip. He's trying to reduce it a bit relative to front grip, since Stock classes have fewer ways to change a car's at-the-limit behavior.



Scott
90SM

 

I'd lay odds that you couldn't visually tell the difference, unless you sat there and watched the tire being inflated.

I haven't personally had to run 60psi, but with a previous STS car the fronts actually required 52-55psi for best grip for some tires in 225/50-16. They looked just like they did at 40psi.

Older FWD cars with taller profile tires would frequently run 60psi+ in the front. 185/60-14 was considered low profile in the 80's, as was 225/50-16.

Autocrossing can drive some pretty funky setups in some classes. You just have to use what works for your car and situation.

Scott
90SM

 

42 -45 up front, 50++++ in the rear. Running 60 in the rear on concrete is not uncommon. My rear camber is not optimal @ -1.5.

I'm betting the bead wasn't seated.

 

I've had the lube (that they use to get the tire onto the rim) sorta spray out onto the sidewall before on 710's (and some other tires, to a much less extent). It made me a little nervous, but I never seemed to lose any air pressure, though.

Glad you didn't have a serious incident!

Edit, by the way, I always ran over 40psi in my 710's, too. No biggie.

 

The tire was a total loss after 3 events. It was damaged to badly to remount

 

We always use to run 60 in the rear of our 05-06 MCS.

 

IMHO, there is no one absolute tire pressure setup. The tire pressures have to be set to the driving style of the driver and the car setup. I've had co-drivers before where the pressures were set to their preferrence; they did very well while I thought the car was an undrivable pig. You have to find what works for you on the surface and conditions you're running on.

Personally, I start every event for both Hoosiers and Kumhos at 43F/38R. Most of the time, all I have to do is bleed off the temperature induced pressure gain. I may juggle the pressures a pound or two, but that's it. It works perfectly well for me. YMMV.

 

That has always been my settings---42f/36r. Isn't setting the rears that high just covering a mishandling car? I am not trying to start a war here, just never heard of running that high a pressure. I know you can play with the rear pressures to help with under/oversteer but have never seen pressures that high before.