Hiya, I've recently bought as XS2 and am looking to get some new tyres/rims. At the moment they're standard at 18" x 4.00 rear and 19" x 3.50 front. I'm using this bike as a donor so i can turn it into a bobber. Can anyone give me some advice on what size to go for. I've been told 16" rear 19" front. But reading more online people are saying 21" front. Are there common sizes that are mostly used to get the bobber look?