I put new rims and tires on my FD. 18x8.5 ET40 with 235/40R18. (There was a reason I went with the relatively narrow 235mm btw although I know many of you will say I should have gone much wider.)

My question is about what pressure to run the tires at. Mazda recommended 32psi for the stock 225/50R16s. What pressure should I run these new tires at?

 

30-32 is fine for the street.

 

Basic tire pressure will vary depending on tire load and tire size. A tire with more internal volume should use less pressure. A tire with less internal volume should use more pressure. To be in the ball park, contact the tire manufacturer

My rims are 9X17. When I went to 245/40-17 front and 275/40-17 Yokohamas, I contacted them about their recommended pressure for my car. Based upon the FD weight and weight distribution, they gave me this starting point: 34 front and 26 rear. It works great for the street.

 

I suggest you stay with the Mazda tire pressures.

Dave

 

That is what I've done, but I was just wondering about the very issues that cewrx7r1 mentioned. I think contacting the manufacturer is a good idea.

Thanks guys.