Hoosiers

[SonnyJack]

Having a blast here at VIR but have a question about starting and ending temps for these tires. It's a cloudy 53 degrees here so I just started my first session at 36 psi and ended at 43. Seems high (43) but the car stuck well for the entire 30 min session.

Any thoughts?

[dparm]

Originally Posted by SonnyJack

Having a blast here at VIR but have a question about starting and ending temps for these tires. It's a cloudy 53 degrees here so I just started my first session at 36 psi and ended at 43. Seems high (43) but the car stuck well for the entire 30 min session.

Any thoughts?

Here is a document from Hoosier on this very subject:
https://www.tirerack.com/images/pdf/warranty/HO0914.pdf

Your cold pressures are probably too high, but you will also want to use your first lap to get heat in the tires.

[DRLane]

Originally Posted by dparm

Here is a document from Hoosier on this very subject:
https://www.tirerack.com/images/pdf/warranty/HO0914.pdf

Your cold pressures are probably too high, but you will also want to use your first lap to get heat in the tires.

Thanks for posting. The bit about A7/R7 not being applicable for high speed road course (Watkins Glen is specifically referenced) is interesting. Any insights there? Also less negative camber if so.

[tsk94]

If the tire is wearing evenly and sticking well at ~42psi hot, then I wouldn't have an issue running them at that pressure myself. I know some people run hot pressures with these in the low to mid 30's, and while they will be fast at that pressure, they may not wear even if the tire is rolling over onto the sidewall excessively.

I think 38-40 hot for the porky E9x M3 is a good starting point for this tire given the recommendations from Hoosier. From there you can adjust accordingly. If you start to drop the pressure just monitor how the tire is reacting and how much it's rolling over. There should be a mark on the sidewall/edge of the tread to indicate the max you want the tire rolling over.

[kayha12]

I do time trials on 295/30 A7s - they seem to do well for me around 35-ish hot. And when I mean hot, that means a "cool down" lap at 75% pace then checking pressures at the paddock. Keep in mind I'm only doing about 3-4 flyers at the same time.

This was also last weekend at VIR

[dparm]

Originally Posted by DRLane

Thanks for posting. The bit about A7/R7 not being applicable for high speed road course (Watkins Glen is specifically referenced) is interesting. Any insights there? Also less negative camber if so.

No clue why they say that. I wonder if they're trying to advise it against sustained usage on banked/ovals due to how it loads the tire? Remember the Michelin F1 USGP debacle? :-p

Just give them a call, their tech support is pretty helpful.

[SonnyJack]

On an unrelated question, any harm if I put the car in the trailer still shod with the R7's? Next event is probably end of May.

Rained a bit last session and while probably not enough to have any issues I backed off and didn't push. Hopefully the next to last session will be all dry.

[tsk94]

As long as the temps don't drop low you'll be fine with keeping them on the car in the trailer. The tires will be a bit square initially from sitting for a while but that'll go away quickly.

[dparm]

Originally Posted by SonnyJack

On an unrelated question, any harm if I put the car in the trailer still shod with the R7's? Next event is probably end of May.

Rained a bit last session and while probably not enough to have any issues I backed off and didn't push. Hopefully the next to last session will be all dry.

It'll be fine. Just do some aggressive weaving, hard accelerating, and hard braking on the out lap to warm them up.

[Richbot]

I've found their setup guide to be very good for maximizing the wear/performance trade-off. You need surprisingly high cold pressures on the Hoosier on a heavy relatively high-hp car
If performance is the first goal, I think their pressure recommendations are pretty conservative, but if you want session-long stability and decent wear, they're pretty close to spot-on as a starting point

I've found they respond very predictably to lower pressures ie - you get a great few laps out of a low cold pressure that might squeeze a better laptime than you can ever do starting higher, but by the end of the session, the tire has built a lot more heat and is harder to "bring back" from a slidey lap

These are interesting setup decisions though - when in the session do want to be quick, is it your first time on the track you've never seen before? Then you'll need the tire to be there at the end when you've got it wired into your brain; or have you done 2000 laps of this track and need those first two flyers in cold air in the morning to be the best?

[Richbot]

Originally Posted by tsk94

If the tire is wearing evenly and sticking well at ~42psi hot, then I wouldn't have an issue running them at that pressure myself. I know some people run hot pressures with these in the low to mid 30's, and while they will be fast at that pressure, they may not wear even if the tire is rolling over onto the sidewall excessively.

I think 38-40 hot for the porky E9x M3 is a good starting point for this tire given the recommendations from Hoosier. From there you can adjust accordingly. If you start to drop the pressure just monitor how the tire is reacting and how much it's rolling over. There should be a mark on the sidewall/edge of the tread to indicate the max you want the tire rolling over.

ya what he said, also, take a mm or 32" depth gauge with you to check the divots for depth across the tire too (or just make one out of a piece of paperclip or something and a ruler with fine enough measurements) so you aren't relying on reading to see wear, as they can get some "groove of doom" center wear that isn't always immediately apparent from "reading" the tire

Also, if you're on a small roval like my local track, all bets are off for the outside tire, if your car is fast enough to be on the limit on the banking it's a survival game