KTM 790 Adventure R rider – AdvRider.com. And then a self-proclaimed ‘expert’ weighs in with this controversial post: “I have a lifetime of experience racing mx and riding dirt. This is some of what I’ve learned; Yes I’ve bent the front rim. That only tells me I needed a stronger rim. Front tyre size: 90/90 x 21: Rear tyre size: 150/70 x 18: the KTM 790 Adventure R is created with higher-spec WP XPLOR suspension, From new front tire is leaking air, and when spoken to Tire choice plays a roll, but I'm currently finding as low as 13 rear and 16-20 front is pretty awesome. That is with tall, stiff tires and offroad rims (2.1/3.5, D606/D908) in AZ rocks. Any lower and I worry about spinning the tire without rimlocks, and you can feel the front wallow around, especially connecting trails on pavement. sb2J.