Tyre pressure question - gone from standard 16" to 17" (225/45x17) - what pressure?

[impster]

Hi all.

Car is a year 2000 Audi A4 (B5 chassis) 1.9 TDI SE with the 115 output engine.

Just put some nice 17" alloys on, with 225/45x17 tyres.

Anyone know what the pressures should be? on standard it stated 32psi all round, I've done some maths (which helps compensate for diferent sizes/pressure/air volume etc), and I'm caclulating that I need to be around the 34.5psi mark to 'match' the originals.

Does anyone know for sure what the 'standard' pressure should be for my car on 17"s?

Many thanks

Impster

 

[aragorn]

S4's on 225/45r17's default pressure is 36psi, however they're a bit heavier than a FWD so that perhaps accounts for the difference in pressure between your calculated value

If you dont mind, could you post up the maths used? Would be useful to have them handy to calculate this for the future!

 

[impster]

Pm sent mate.

If someone could tell me how to put an 'attachment' onto a post, I'll post up the excel file i've made.