Just fitted the 18s ( will get some pics up ) and the tyre guy put 40 psi in them
He said thats right but who am i to argue so i though i'd better come here and ask the question

225 / 40 ZR x 18

Anyone care to set the record straight

Regards
Ian

 

What tyres? I run 37f 35r for preference

 

As its quite a broad title does anyone know what the best pressure is for 225/45/17 and 215/45/17 as well?

So thats
225/40/18 =
225/45/17 =
215/45/17 =

 

i run 34 on mine front and back

 

36 front 34 rear on 235/40/18 Sessantas

 

As in does it work for you? What size tyres are you using? My local Subaru specialist said that the standard 16 and 17s work best with 28psi all round. Not sure if thats right but I tried it and it drove well but didnt feel as sharp or quick.

 

Thats quite a good idea

Anyone able to fill it in

 

what about 215/40/17 ive been running 33f 31 r toyo proxies

 

So thats
225/40/18 =
225/45/17 =
215/45/17 =
215/40/17 =

 

yeah works for me, and they are 215/35 ZR 18's

 

32 front 34 rear , thats what i run !

 

--------------------------------------------------------------------------------

So thats
225/40/18 =
225/45/17 = 32 front / 28 back
215/45/17 =
215/40/17 =

 

Read this old thread.

 

Played this game....

Tyre maker says see car manual.

Car makers say ask tyre manufacturers.

So I run +2 psi F & R over Subaru's advised pressures, more on track.

225/45/17 or 235/35/19

HTH

dunx

 

I run 235/45/18 and have 34 front and 32 rear.

 

So thats
225/40/18 =
225/45/17 = 32 front / 28 back
215/45/17 = 34 front / 31 rear Bridgestones RE50
215/40/17 =

I did 10000 miles and got very even wear at these pressures. So would you lower the pressures slightly for a wider tyre i.e. 225/45/17? I have just bought some Vredestein Sessantas and no idea what to inflate to so just kept it the same.

 

Is the general rule the more cm3 of air the lower the pressure and vice versa?

 

And in English

 

Would you decrease the pressure as the internal tyre volume gets larger? e.g. 225/45/17 would run at a lower pressure than 215/45/17.

 

erm.........ok

I'll drop it to about 36 and see how i get on