I've got one in the front, because it came with the KTM wheel. Think it's a standard KTM plastic one, no idea what size. Don't have one in the back, and never bothered putting one in my Yam front.

Haven't had any issues in a year of rallying and a whole load of trail-riding, ran as low as 18psi at the Ryedale, but more generally about 23-25psi. I'd agree with Phil's thinking that you'll start getting pinch flats and/or denting rims before you spin tyres on the rims.

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I spent a lot of money on travel and racing motorcycles - the rest I just squandered.

XT660Z - Commuter, Adventurer...Racer?

www.dashmoto.net

Other bikes >> MT-03 / CG125BR-J / ER-6F
Departed >> ZXR400L3 / EC300 / DR-Z400E / DR800S / GPZ500S / GS400