Morning all,

Last week I enquired locally about tyres for mine (2012 Westminster 4.4 TDV8). I was unsure whether to replace the 2 x fronts that are very worn with Scorpion Zero's, as that is what is on there now and the rears still have 4-5mm on them, OR replace all 4 with Grabber AT3's?

When I asked my local tyre fitter for quotes on 255/55/20 and 275/45/20 they asked whether my rims would take the 275's?

Fully understand where they're coming from with fitting a 275 tyre to a rim designed for a 255.

Once these Scorpions have worn out, I'll be looking to fit Grabbers all round, but would like the knowledge to be able to tell the tyre fitter that 275's will be fine, or not?

Thanks in advance.

the 255 50 20 tyre size is on a 8.5j rim, the 275 45 20 ideally should go onto a 9j rim but many have fitted these onto a standard 8.5j rim and have had no problems....

Cheers Stan.

I can see the tyre fitters concern for legalities, etc. They were just as concerned about putting new front tyres on with half-worn rears (but that was probably more to do with them wanting more coin, not about the diffs!).

Much appreciated Sir.

I have 275/45/20 General Grabber AT3's on my 8.5" rims, all is fine and run well

I would never run different sizes new/old, and would keep the wear even, i.e. fit 4 new tyres at the same time, same size.

275/45/20 are the same rolling dia as 255/50/20, in theory, 255/55/20 are +3% Regards
Royston

2008 4.2 Supercharged Autobiography
1994 Classic Vogue SE
1999 Rover BRM
1987 Rover Vitesse Twin Plenum

Cheers Royston,

Surely a half worn rear with 4-5mm of tread left, and new fronts with 8mm won't cause problems? The rolling diameter difference must be minimal, something like 0.3%

In theory, with open differentials, couldn't do it on my old classic with a viscous coupling.

Not ideal, the Grabber AT3's tread depth is 9mm new, measured them today  Regards
Royston

2008 4.2 Supercharged Autobiography
1994 Classic Vogue SE
1999 Rover BRM
1987 Rover Vitesse Twin Plenum