Tire pressure in Kumho MXs

SDVette · 06-09-2003, 05:34 PM

I recently replaced the GY runflats on my C5 with Kumho MX tires. I always ran the GYs at 30 PSI cold. They would rise up to 36 PSI when heated.

The tire installers set the pressure to 35 PSI on my new Kumhos. I recently was cruising in the central valley of California where the air temp was 108 degrees. After several hours at 80-100 MPH, I started getting "over pressure" warnings from the DIC as the tires had warmed up to 42 PSI.

I know the max pressure spec on the Kumhos is 51 PSI, so I was not too worried, but I am wondering what is the best pressure to run these tires for even wear?

gpflepsen · 06-10-2003, 10:28 PM

I would say 30 psi for daily driving. Just like the runflats.

SDVette · 06-11-2003, 08:49 PM

Maybe, but I was thinking that with the softer sidewalls, perhaps more pressure would be required? Any other opinions?

gpflepsen · 06-11-2003, 09:44 PM

Keeping the same sized tire you'd want to run the same pressure as stock. The same sized tire will give the same contact footprint at the same pressure, and that is what you want.

If you're carrying heavy loads (not applicable to corvettes) you need more pressure in the tire. Just think the tire psi is carrying the vehicle weight via the area of the contact patch.

Increase the tire contact patch with larger tires and the required pressure will go down.

Without air, the runflats only support the car on the sidewalls. You still need the air to force the tire off the sidewall and onto the tread.

Look on the door of the car, it gives you the pressure for the stock tire size, 30 psi.