I have 245/50/16's but they are not the stock size for my RS so how can I be sure what the tire pressure should be?

 

30 pounds for my IROC.

JamesC

 

That's what I put in them, but is that opinion or fact?

 

A cold, hard fact from the door placard. Good luck.

JamesC

 

It will greatly depend on the tire brand and quality.

Modern tires far exceed the sidewall design and footprint bulging of tires made back in the 80's when these cars were made and those door placards were affixed. Sone tires can run 30psi, some can run much higher. I will give you an example.

I ran a set of Goodyear GSD3 tires 245/50-16's on my car with a 51ps1 max presure stamping on the sidewall. I successfully ran pressures of 49 on the fronts and 46 on the rears for 3 years daily with also some light roadcourse and two autox events. I was able to get 25,000 miles out of them on those pressures. I had then put some crappy BFG KDW tires on the car with a 44psi max rating and I was only able to run 38 fronts and 33 rears on the same car only with different tire brand. Running them higher would dome the center contact patch.

Dean

 

I tried various pressures with some 44 max psi Goodyears (IIRC), but always came back to 30 pounds. The ride simply felt better.

JamesC

 

So the Iroc/Z's had 245/50/16s as a stock option?
I have an RS which did not have that size as stock so MY door sticker isn't gonna be gospel.

 

A few years in, GM went to 16" wheels as the "performance" configuration on our Gen 3 cars. 245/50-16 was the tire size.
I'm sure someone can chime in with the exact year they appeared.

 

My 16's on my 92 are stock, just the tires are bigger than the 2 sizes listed on the door sticker

 

That is what my door says, but I run 32 front and 30 rear for street driving (245/50/26 BFG G-Force KDWs) and when I autocross, I usually run 46-49 front and 39/42 rear depending on temperature/weather and course.

 

I found KDWs (275/40/17s) worked better with less pressure at least on road courses worthy of the name. For them hot about 38 front and 33/34 rear depending how the track feels on a given day. I once ran the fronts up around 42/44 hot (-1.5 camber) and the second row of tread blocks started to wear worse than the outer row - so over inflated for sure.