jz78817

your recommended tire pressure is dictated by the car. you don't change it based on the tire size. fill them to the pressures the door tag says.

Norm Peterson

No. The door tag assumes that the car is still on OE-size tires (and you'll note that the door tag also identifies what that size is).


OE pressure recommendations are pretty heavily based on having adequate load capacity (so that the tire will not over-flex and consequently overheat), and this is a function of tire size (Load Index), load category (Standard Load, eXtra Load, Light Load), and inflation pressure. When you change the load index by going to a larger tire (bigger Load Index and generally within the same Load category), the tire's rated load at that (say) 32 psi goes up. There is no need from the standpoint of maintaining the car's necessary load capacity to maintain that 32 when you upsize the tires. Better not to, as you could be overinflating the tires enough to increase center tread wear.


But you don't have to take my word for it, as there is a Tire & Rim Association procedure specifically for setting equivalent load capacity when you change tire sizes. Really. And FWIW I have put together a spreadsheet that can do the lookups from the tire load vs inflation pressure tables and tell you what you'd need to match the OE rated load.




Norm

Urambo Tauro

You can also do the chalk test.

Start with a good alignment and a ballpark guess tire pressure. Use chalk to draw a line across the width of the tread. Drive it, and see how the chalk wears. Try different pressures until the chalk wears evenly. That's how your tires will wear.

ghunt

I just realized I never got anyone pictures of these tires...oops.

I've finally gotten to the point where these tires are low enough on tread to be dangerous. I've had them 3 years but they probably only have about 30K on them, so that's a bit disappointing. I've actually been really bad about rotating them but they've worn pretty evenly front and back, they're down to the wear bars in back and very close to it up front.

Wanted to change up brands but I found out hardly anyone else makes this size. DTD is offering $135 in rebates on a set of Nittos (expires after today), I was considering the Hankook Ventus but $135 on the Nittos is basically a free tire (and the Hankooks are only $12 cheaper per tire). Might just go order them tonight.

Nuke

I always experiment with new tires, typically starting at the door placard value and then going up or down 1-2 psi at a time. 80% of the time its up.