What tire pressures should I run?

[Phokaioglaukos]

Larry Herman wrote:

The ideal way is to take tire temperature readings. This will tell you how effectively the tire is working across the width of its tread. The outside and middle of the tread should be approximately the same temperature, with the inside usually being cooler. If the center of the tread is cooler than the outside, you need more pressure, and vice versa. Tire temps can also show the effectiveness of your camber and toe settings.

Good stuff, Larry, thanks for posting.

When I ran the OEM Pirelli Rosso tires I changed from the owner's manual 32F/39R cold to 32F/32R cold and looked for the tires to be 38-40F/38-40R hot. I kept doing that when I changed to Toyo RA-1s about the middle of last year (I drive to/from the track on the same tires).

Now I have invested in a contact pyrometer that has a memory function. The operator presses the probe into the carcass of each tire at three locations across the face of the tire to evaluate the alignment. It also lets me see if my tires are at the right temperature. Manufacturers advise temperature ranges for their R tires, even the semi-R tires like the Toyo RA-1s (which I have) and the Nitto NT01s (which I will install after Shenandoah).

According to Toyo, the RA-1s want to be 160° F. to 220° F. Toyo also says that the target hot inflation pressure for these tires is high 30s to low 40s. I think over 40 is a bit much. Toyo also recommends negative camber of from 2.0° to 5.0° and advises that inside shoulder wear will result. Toyo says to maximize tire life , the tire should be dismounted from the wheel and flipped when the tire is about half way worn.

According to Nitto, the optimum operating temperature for the NT01s is also 160° F. to 220° F. Some on Rennlist have asserted that the NT01s have the same rubber compound as the RA-1s. I sure do not know.

Others can discuss Michelin Pilot Sport Cups, Hoosiers and slicks. I'm too inexperienced (and cheap) to move to those tires, and also lack the second set of wheels, trailer and tow vehicle they can require.