Unusual tyre sizes on Focus mk1

[lionrampant]

Gentlemen, I have recently acquired a Mk1 Focus that had aftermarket alloys fitted to it. They're running 205/40/R17 rubber - but I can't find official pressure numbers for that size of tyre on a Focus anywhere.

Any thoughts what they should be at?

[alangla]

Purely a best guess - I'm running a Mk2 Focus CC3 diesel on 205/50R17s - recommended pressures are 33 on the front and 36 on the back IIRC, but bear in mind I've got all the hydraulics for the roof in the rear & a 2.0 TDCi lump up front. I imagine 33 all round will be a reasonable estimate.

[lionrampant]

alangla said:

Purely a best guess - I'm running a Mk2 Focus CC3 diesel on 205/50R17s - recommended pressures are 33 on the front and 36 on the back IIRC, but bear in mind I've got all the hydraulics for the roof in the rear & a 2.0 TDCi lump up front. I imagine 33 all round will be a reasonable estimate.

Cheers, thats as close to a reasoned guess as I've found so far

[neiljohnson]

205/4017 was never a stock fitment on the Focus so that why you cant find any official figures for them.

With non stock sizes it can be a bit trial & error what i would do is set the pressure to whatever the stock pressures for your car & then keep an eye on how the tyres are wearing.
Wear to the outer shoulders increase the pressure, wear in the middle lower it, do this a couple of psi at a time till you find a happy medium

[XslaneyX]

Got this tyre size in my focus and i think all round is 33psi. Will try and find out properly next week

[lionrampant]

Thanks lads, think I'll put it to stock for now and see what happens - though if XslaneyX comes back with numbers that'll be great.

[XslaneyX]

My friend at the garage reccommends 32 psi all round and for extra load then 34-36 on the rear. My tyres were at 32,33,35 and 39psi when we checked! Car seems to feel better on the corners now.

Hope that helps matey