I've just upgraded my tyres from the stock Bridgestones to Dunlop GT501. Front is 100/80x19 and rear 140/80x17. I found them quite heavy in my first ride and I think this is what others have found also with the 501's. Apparently this eases once they've worn in. The dealer said it would be around 100km before they are properly scrubbed in. What have others found.