imperial to metric XR250 TYRES HELP

[xr250r]

hi i have a honda xr250r 2001 plate and i want to change the tyres from knobbly to a more road biased type but im confused about sizes. In the owners manual is says the front is 3.00 - 21" 51p and the rear is 4.00 -18" 64p. on the bike on the front at the moment is a 90/90-21 and on the rear is 120/90-18 but im not sure what the rear should actually be in metric any ideas? thanks alot

[Mervinh]

sounds about right to me, the RD,s used 350/18 rears and that translates too 110/80/18 and 300/18 fronts which translates too 90/90/18

[xr250r]

ah so 120/90-18 is fine and i can just buy new tyres in the same sizes already on the bike, thanks man

[AlanH]

XR rims are the same as my CRM. I was told by Avon that the best road only fitment is 90/90 21 on front and 110/90 18 on the rear in Avon RoadRiders. Distanzias are also available in those sizes if you don't want road only tyres - and of course there are plenty of others to choose from too.