tyre pressure puzzle

[saw09]

:1zhelp:Hi, I'm new to posting on this site so I'll apologies if this has been answered umpteen time before.

I've got an A4 avant tdi 1.9 quattro, 2002. When I got it the previous owner had put some low profile tyres on it so when I look at the manual or label to get the correct tyre pressure my tyres are not listed.

The tyres on the car 225/40/ZR18. I had various differing answers form tyre fitters, mechanic friend web site etc so I'm hoping some one out there can help!! The manual ranges from 34 - 42 depending on size and load, the tyre fitter said 28 and when I type my reg in to a tyre website I get 30.

Does it depend on the tyre or the type of car?

Thank you in advance :confused:

[fourringsrus]

Yes the size of the tyre in relation to what it's fitted to can make a difference to required pressure
Though I think there may not be an exact science to this it might be worth chatting to other owners who have fitted 18" rims to their A4's
Some of the later A4's were fitted with 18"'s so you should get some feedback quite quickly
Stuart

[bez101]

32 should sort u
but it all depends on you

[RickT]

On a 40 profile I would be looking @ around 38-40psi.

I run my 235/45/17's at 40 PSI, due to all the pot holes where i live to save any rim damage..

[warp_speed]

Need to be careful, my a4 came with the RS4 wheels, 235/40 R18 manual says 42psi all round.... I've just found my tyres have worn in the middle, looks like they were over inflated, currently got them at 34, need to buy new tyres anyway, so I'll see how I get on with them for the moment

[danclyon]

On a 40 profile I would be looking @ around 38-40psi.

I run my 235/45/17's at 40 PSI, due to all the pot holes where i live to save any rim damage..

OUCH really? The roads are pretty (very) crappy round here too, and I still don't run mine of the same size at any more than 32 as they are too harsh after that and wear on the hip excessively......that said though, the chaps at the tyre place in town said for that size tyre it should be 38 as 32 is way too soft....but they are also the people that told me my flat had been driven on for several miles and was wrecked, when in reality it had just gone down overnight parked on the street - and ATS repaired it in 20 mins....

Cheers,
Dan.

[saw09]

thanks everyone.