I've seen these tyres fitted to 20" wheels in adverts:

Quote:

275/45/20 cooper zeon lt
275 55 20 nitto terra grappler
The 275 55 nittos are about two inch taller and the speedo reads slightly under 31 mph on sat nav to 30 on the speedo.
285 50 20 cooper zeon lt
The 285 50 coopers are about an inch taller than standard. The speedo is correct with these tyres as the normal size read under speed.

indeed you have mr mong....until recently i myself have been running on 295/45/20 tyres on RRS wheels... ..............................




this is handy