I already have the 38, tried to put it on rear but wouldn't clear the kickstand bar so put a 35 Schwalbe Marathon Plus in rear and still have the original Bontrager front tire; was thinking that I'd like to have Marathons on both tires and since I have that 38 just sitting around; would've preferred 38s on both but can see even with a 35 on rear there's not much clearance left (I think the Marathon's are taller than some others?)