Best tyre pressure for 18" rims?

paul10

paul10

Forum user
Dec 19, 2009
27
0
Basingstoke, Hampshire
Evening All,

I've managed to source some cheap 18" rims for my
Cat, they have 225/40/18 rubber which I think I'll stick
with at the mo.

Gonna fit them this weekend along with new drop links
and was wondering about tyre pressure?

Can any of you guys with 18's give us some input as to
what would be best or what works well for you?

Many Thanks

Paul :)
 
I run mine on around 36 PSI. I find anything lower just seems to feel like they are flat all the time. I know some people put as much as 40 PSI in them. I think the recommended amount is 32 PSI but I am not to sure TBH.
 
I run with 38psi all round and get fairly even wear (225/40R18 and 30mm lowered).
Lowering is another factor to consider as this changes the camber so lowered cars will tend to wear more in the insides.
Increasing the pressure will also help with this.
 
FlamencoAssassin said:
I run with 38psi all round and get fairly even wear (225/40R18 and 30mm lowered).
Lowering is another factor to consider as this changes the camber so lowered cars will tend to wear more in the insides.
Increasing the pressure will also help with this.
Click to expand...

Ditto, I run exactly the same tyre and rim size and the same pressure
 
FlamencoAssassin said:
I run with 38psi all round and get fairly even wear (225/40R18 and 30mm lowered).
Lowering is another factor to consider as this changes the camber so lowered cars will tend to wear more in the insides.
Increasing the pressure will also help with this.
Click to expand...

Richb said:
Ditto, I run exactly the same tyre and rim size and the same pressure
Click to expand...

Double Ditto, Lowered 30mm on the eibachs same as you Manos, I run exactly the same tyre and rim size but 34psi so maybe worth trying the same pressure as you two.
 
I ran mine on 38psi, and after lowering had the toe tapped in 1 degree also. The 225/40R18s on that lasted 20k and still had loads of tread when I traded the car in and sold the wheels to Spikey who drove at Mach2 over a roadworks ramp and buckled them all shortly afterwards.
 
jamie_duff said:
I ran mine on 38psi, and after lowering had the toe tapped in 1 degree also. The 225/40R18s on that lasted 20k and still had loads of tread when I traded the car in and sold the wheels to Spikey who drove at Mach2 over a roadworks ramp and buckled them all shortly afterwards.
Click to expand...

I don't suppose you remember the toe setting Jamie?
 
Long time ago Al, but I seem to remember we shot for 0deg but ended up with about 0.2deg toe-in, which is not what you normally find with FWD as it reduces steering sharpness a touch, but I ran out of time and just stuck with it. With the 18" wheels and the slightly wider offset the steering still felt miles better than the OE 16" wheels anyway :)

Should add these were just mechanical gauges with the spring loaded wire between two protractors rather than a modern laser set up, so the initial and final readings probably weren't very accurate anyway! It was about one degree of toe-out we removed according to the gauges though, and whilst I don't know if I'd have had excessive wear at the factory toe angles, it certainly worked well on the 18s. I was pretty hacked off with Kumhos which lasted 8k before the inside shoulders vanished within the space of 2k, and I wanted to do something before putting the 18s on with the (then) expensive tyres.

In hindsight, it was probably just the elcheapo Kumhos doing their usual uneven & random wear tricks. The Bridgestones on before the Kumhos wore perfectly evenly down to the legal limit before I changed them.
 
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