Widest tyre on a 7J rim?

[MrFlibbles]

are 235s too wide for 7Js?

[GreenV8S]

Yes, too wide. General rule of thumb is rim width plus one inch for road tyres, plus or minus half an inch. 205mm is about right for that rim.

[interloper]

Have to agree with GreenV8S here, the ideal tyre width on a 7J is 205. You can get away with 225 but for best results (handling wise) 205 cross section is the way to go.

[GavinPearson]

235 is possible.

Every manufacturer designs their tyre to suit a range of rim widths and each tyre has an optimum. You can obtain the data from the manufacturer direct.

I know the Jag XJS used a 235/60 VR 15 tyre on a 7J rim HOWEVER the actual dimensions of the tyre were closer to a 225/65, it came within the tolerances allowed though so it got badged as a 235/60 because that seemed 'sportier'.

What confuses many is that road tyre width is the width at the sidewall whereas slicks are measured as width of tread.

A slick should be fitted to a rim ideally 1" wider than the tread width to control flex, on a road car you want it to be pleasant to drive so flex is to some degree desirable.

Again, you need to follow the manufacturer's recommendations.

[Pulsatingstar]

Presume on the XJS example it fitted due to the large sidewall taking the flex. If this is a 17 and something like a 40 profile its going to be a bit different.

[MrFlibbles]

Im thinking 235/40/17. Thats what I have on my rears at the moment, but im looing to change my wheels. The particular wheels im after are quite rare in 7.5J, ad I dont want to lose grip at the rear end.