RE71-R AX pressures Options

[mskala]

Does anybody run the RE71-R on their 914 for autocross? I couldn't find any thread
discussing pressures. Going to these from hoosier for this year. Narrow body car,
so I am using 205/45/16.

Based on other types of cars , search of other sites leads me to think high 20's for a
light car.

[wobbletop]

Current issue of Grass Roots Motorsports has a tire shootout.

Because of the stiff sidewalls they are fairly flexible with tire pressures. Looks like the best skidpad time was with 24-27 lbs. Up to 34lbs only reduced times a couple of %'s.

[mskala]

Great! we'll see how it goes.

[Krieger]

It seems like mine end up at 28 psi in the front and 30 rear hot when I autocross. I am using a pyrometer to check temps across the tires. My tires are 205/50/16. I love these tires!

[mskala]

Thanks. There may be rain sunday so I might not be able to even fully use them yet.

[DRPHIL914]

I thought Bridgestone was going to stop making these, - I have 205/55-16 on car now, and was considering dropping to 205.55- 45 seems really small, ok for AX I guess but would really make RPM's high for street correct?

[914 Ranch]

The lighter the car the less pressure. I was using 14.5 pounds in the front and 15 pounds in the rear in a car that weighted under 1650 pounds. Kumho's 225/50/16's. The guy's I asked running this tire on 911's were running 31 psi. I think the car was over 3,000 pounds. A pyrometer is your best friend. It will help you get your tires on the ground. I take measurements in 3 places (inside, center and outside) on each tire and adjust the camber and air pressure to make the measurements all within 10° watching for scuffing on the edge of the tires.
Did all that make any sense?
Joe

[mskala]

I thought Bridgestone was going to stop making these, - I have 205/55-16 on car now, and was considering dropping to 205.55- 45 seems really small, ok for AX I guess but would really make RPM's high for street correct?

I'm not going to drive around on these except to events. And most of the reason
I upgraded my motor is to get 7100RPM limit. I can get to 63mph in second.
4-cyl guys will have different ratios.

[mskala]

A pyrometer is your best friend. It will help you get your tires on the ground. I take measurements in 3 places (inside, center and outside) on each tire and adjust the camber and air pressure to make the measurements all within 10° watching for scuffing on the edge of the tires.
Did all that make any sense?
Joe

I get you, but it's probably more than I want to do. I'm trying to use 'street' tires
since I'm going to lose due to PAX anyway, and I'm getting old to be changing
tires twice at events in the 90+ degree heat.

I talked to my friend with a 904 kit, he sometimes uses these, and his car weighs
about 1700. He went down to about 22 pounds.

Yesterday I was using 27 all around, and didn't touch the arrows on the sidewalls.
I should attempt lower next time.

[914 Ranch]

I get you, but it's probably more than I want to do. I'm trying to use 'street' tires
since I'm going to lose due to PAX anyway, and I'm getting old to be changing
tires twice at events in the 90+ degree heat.

I talked to my friend with a 904 kit, he sometimes uses these, and his car weighs
about 1700. He went down to about 22 pounds.

Yesterday I was using 27 all around, and didn't touch the arrows on the sidewalls.
I should attempt lower next time.

Yes, I believe that you should never stop playing with the pressure and the camber. Watching for the scuffing on the inside of the tires too. I forgot about the inside of the front tires. Even with the temps within 10° (at 6 points across the front) and at 14.5 pounds I was just starting to get scuffing on the outside of the front tires and none on the inside. The backs were perfect with a blue haze scuffed up edge and temps within 8° across the back. In the front I needed less camber and pressure even at 14.5 pounds, gotta get the fronts to stand-up a little more. I changed the camber and then I bought new tires so I am starting over (BF Goodrich Pro Comp 2 a/s 225 16's). I will probably start with 15 psi in the rear and 14 psi in the front. We'll see what happens.