Webz

I am running new with full tread Toyo RA1 305/35 18 all 4 corners on a 2000 coupe w Z06 suspension (-1.2 f & -0.9 R camber) at Putnam this Sunday. Looks like temperature will be 53 ~ 68 F. How does cold pressure of 33 front and 31 rear sound? How does hot pressure of 40 front and 38 rear sound?

Thanks

ibjamin

I think those will be high. I think a mid 30's hot would be better. Watch the tire rollover on the sides and add pressure if necessary. Also the difference between front/rear will probably be less. Should be close to the same value.

My .02$

George

gkmccready

Quasi-useless: I used to autocross a second gen RX7 with RA-1s and I'd start them 32psi cold for that application most of the time. They didn't work nearly as well at higher pressures. At full depth they were always ultra-greasy, too.

C6400hp

I run the RA1 on my C6 275/35Front 305/35 rear at 38psi hot all the way around. Seems to work very well for me. My camber settings are very close to yours -1.3 F -1 rear.


From another site
"How to setup your Toyo Proxes RA-1s The Toyo Proxes RA-1 comes molded at 8/32” of rubber, which is quite a bit of rubber for a race tire. There are two reasons for shaving:
Shaving makes the tread blocks shorter. This keeps the tread from rolling over during cornering and prevents the building up excessive heat - two factors which can lead to chunking and thus premature wear. Shaved tires will ultimately last longer for track use!
Shaving makes the tire faster sooner. Excessive tread block movement makes the car feel unstable and loose. By shaving the tire, it will be immediately more responsive and strangely enough also helps the tire last longer.

The common shaved depth for a full race set-up is at least 4/32”. One characteristic of the RA- 1 is that unless you shave them, the tires will take time to run in. Meaning that if buy a set at full skid, they will not be as fast as they will be when they wear down to 4/32” or lower.

Tire pressures should be started at about 32 psi cold. Usual pressure build up is from 3 psi to 9 psi. This must be taken in account when setting cold pressures. Your pressure should end up in the high 30's to low 40's. If you take tire temperature, the normal operating range of the RA-1 is 160 to 220 degrees. Hot pressures in competition will run from a minimum of 36 psi
hot to a maximum of 46 psi hot, with 40 psi hot being a good starting point. Remember that the tires will build up pressure in competition. These numbers are arrived at with a properly set-up car in mind. Outside temperatures may make it difficult to hit these numbers, but in general these are temperatures you should be seeing if you have a properly set-up car.

All race tires need to have camber adjustments made to get the optimum level of grip. If you have camber plates you will be able to get the most from the RA-1 and any other compound tire. To get the tire to work to its maximum performance, you need to dial in at least 2 degrees of negative camber in the front with stock components, and some creativity, i.e. swapping sides on the stock strut mounts. If you have camber plates then dial in more, say upwards of 3 degrees negative camber or more. This is required to get the car to handle optimally."

Webz

Thanks for the replies, good information.

VetteDrmr

What cold temp pressures you have to start with to end up at 38 hot is what you want.

Have a good one,
Mike

robvuk

Normally I'd agree with this but you're from Texas. Putnam will be darn cold at 53 degrees and tire temps will never get to what you would be used to. I say, start out with 30-32 cold and take it easy the first couple of laps. Build up some heat and check for that rollover. Then inflate as needed.

BQuicksilver

I run 315 NT-01's (very similar tire) and use similar cold pressures at Putnam with the same camber. Sessions usually end with 38-40psi hot. Much past that and you can start feeling them go away.

I think you'll be happy.

I-gotta-Novetta

An advantage of such a lightly attended event like this is it is an ideal test and tune opportunity. Try some crazy tire pressures, go way low, or way high (there is air at the track) and in-between. Watch your times, If you go by car-feel, alone you may actually be slower and not know it. So monitor lap times if possible to see how the different tire pressures affect speed.

You will probably end up liking what everyone else is suggesting, but who knows? I found that my Miata was consistently faster on RA1's at lower pressure at Putnam than the conventional wisdom suggested.

C6400hp

That depends on the ambient, track temp, and setup/alignment. For me it is usually somewhere in the 31-34 psi range cold.

VetteDrmr

Well, then, let me come at it from this angle: you do *not* want to get the tire pressures up over 40 psi, regardless of temperature. My experience has been that they lose quite a bit of grip above 40.

Or, maybe another way to say it: go with 38 psi hot, warm, or whatever thermal energy you can find.

Have a good one,
Mike