Changing front tyre size. Worth it ?

[s6boy]

Currently running 235/40/18's on the front of a 3.6 with Gaz Golds. In need of some feed back from those with experience as to whether it's worth going for 255's instead and if so if I'd need a geometry change as well. My mind was made up until I read a recent post (can't remember where) which said the bigger size increased tramlining.

[T450t]

you will probably get tyre rub on heavy breaking if you dont raise the spring rate and yes tram lining will increase.

225x35x18 work

[T5AMX]

i decided to leave it original when having new tyres... it aint broke so dont try and fix it

[glow worm]

I changed from 255s to 225s on the front on a Mk2 S , and I find it a lot better drive. I doubt if you find much difference between 235s and 225s but with 255s your tramlining will be noticeably greater.

[Whitey]

it's funny as some people and dealers will tell you to go to 255's to help tramlining! I thought that going from 35 to 40 series helps with that? Never tried it though, I'm still using 225/35's and all ok on my RR

[NCE 61]

I actually find my Tuscan S with 255/35's tramlines less than my previous Tuscan with 225/40's.

[s6boy]

NCE 61 said:

I actually find my Tuscan S with 255/35's tramlines less than my previous Tuscan with 225/40's.

Being an 'S' I was thinking along the lines of different geo settings as well as a larger contact patch as iirc the 'S' was designed around the bigger wheels.

[glow worm]

I spoke with Ben Laing (The designer of the Tuscans suspension) and he told me it was designed for 225 tyres , its was Peter Wheeler who insisted on wide tyres not for design reason just cosmetic. An 'S' has stiffer springs than a non-'S' and on MK2 different adjustment on the Bilstiens.

[s6boy]

Interesting one thanks Glowie, stiffer springs may make some difference but I would have thought adjustable Gaz even if not as good(?) as Bilstein would still offer the same rate/range of adjustment.

[glow worm]

I'm no expert, but I think the issue is it's a matter of springs matching damper settings. I used to computer model Jaguar A/C landing on grass strips (incl. The Falklands) and the relationship between damping and stiffness becomes quite critical. Modes of vibration and crap like that....