I have an 08 street glide. Will I have to do any front fender changes to accommodate a 21 inch front wheel? Also what is the best size for the rear without having to make modifications?

 

Drill out the 2 rear mounting holes on the front fender to 3/8". Lift up on the back of the fender as you tighten up the bolts. Install the 21 and tape a 1/4" nut to the center of the tire. Spin the tire and if the nut clears the fender you are good to go. As for the rear, I'm running an 18 X 3.5 with a 150/70 18 tire with stock pulley and rotor and no mods.

 

I knew that worked when changing to an 18" wheel, but does it work with a 21" also? I was told I had to change the fender in order to fit a 21.

 

That is the stock fender drilled and lifted on my bike with a 120/70 21 Metzler. 18K miles and no issues.