Tyre pressure for 18in wheel?
 

Good morning all.
I was just wondering what tyre pressure people are using with 18inch wheels.
Have gone for 34 on the front and 32on the back. Tyres are 225 /40r18

What does your owners manual/handbook recommend (for 17's)? Use those figures. (have seen listed as 36/30 )

35 Psi Front, 31 Psi Rear I run on my 225/40/18 Speedlines. This is as stated by Prodrive in the installation paperwork for the red 05-07 lowering STi spring kit I have fitted they once did. Seems to work for me.

I have the same springs. Will try those pressures :thumb:

Depends on the sidewall stiffness imo. What tyres are they?

Michelin pilot sport 4

92Y or 92W ??

92y extra load

Start with OEM (is it 2.1bar F; 1.9 R?).

See how she feels/handles, then alter by +/-2psi (probably increase only, because of lower profile tyres), as necessary.

Repeat, etc.

Then once settled upon, check the tyre wear pattern is even - say, check every month (but obviously disregard any outer-edge 'roundabouts-based wear', though! :D)...

Oem works out to 31front 27back seems a bit low to me

Shunt 88 is correct. Prodrive do recommend
35f 31r on 18in wheels

That's 2.1 and 1.8 bar respectively. All but the same as for the Classic 205/50/16 tyre.

But yeah, the New, Age have 17" and lower profile tyres (and the car is heavier), which you would have thought would need slightly raised pressure - even as std. That said, Subaru would have arrived at those pressures during the car's development testing, etc.

But seeing as you've gone up by "+1" on the wheel size, then I'd be tempted to raise the pressures by at least 2psi, i.e. to 33 F; 29 R.

And go from there...

I assume you converted the figures from above.....

Every 2007 Owners handbook back page - "Gas Station Reference" info I've looked at (US,EU and RUS) gives 36/30, 35/29 or 36/29 for 225/45/17 90W wheel/tyre combo, so adding 35/31 to the list

Any of the above would would be a good place to start