Tyre size

We are upgrading wheels from 18 to 20”, however the factory standard tyre sizes for each rim reduces the rolling circumference on 20’s (235x60 R18 vs 245x45 R20) from 2322.3mm to 2288.7mm (1.47% reduction).

Alternatively we can fit 255x45 R20 which have a circumference of 2316.9mm, only 0.23% reduction.

Obviously I want speedo to be as accurate as possible, and wonder if there is a reason for this, or if anybody has changed tyre size already?

The price of the tyres isn’t too different wither.
Cheers

Exactly. I fitted 255x45 R20 to my shadow chrome 20'' rims on delivery when new for this very reason, and to be a touch more meaty looking too.

I have a 2011 Prestige with the standard diamond cut 19'' prestige alloys, but painted gloss black.
Tyres are currently the standard 235/55/19 but are a cheap make unknown to me so ive no idea how long they will last or what they are like in winter conditions.
Would a 255/55/19 tyre fit with no issues regarding clearance, scrubbing or rolling diameter ?
Black circles are showing the Avon ZV7 in both sizes, but the 255 is £20 cheaper per tyre than the 235 for some reason.

TIA

Rog

They should fit without any issue

cheers, ill keep it in mind for when its time to change my current ones which were brand new when I got it but are just budget specials so no idea how long they will last given I drive 60 miles a day minimum just commuting.

is the 235/55/19 more expensive because of popularity or because they aren't common do you think ?

Yeah I think more suv’s Use the wider tyres, have a look here:
https://www.camskill.co.uk/m57b0s0p0/SUV..._-_19_inch
you can get a Pirelli for £101 each and should find black circles very close in cost including fitting, and if not could order and have a local garage for them for £10 a tyre

i like the sound of Pirelli for £101