I have a 1990 flhs. I'm wanting to put a 21 by 3.5 on the front but I can't find one with the correct bearing size. I can only find 1 in bearing wheels. What can I do or change to get a 21 on my bike ?

 

Change to late model fork lowers that take the 1" axle, or find a spoke hub for your bike and have a rim laced for whatever.

 

If it has 1" bearings, you could replace those with 3/4", Harley # 9267
or you could use reducers

 

^^^ did not know they made those

 

Fellow 1990 FLHS owner here, bought new! Installing 21" wheels to dressers has really only become popular since long after our bikes were 'modern', so you are presenting yourself with a bit of a challenge. There are plenty of more modern bikes with them, but they use different wheels, bearings and brakes. Your bike uses tapered roller bearings, plus front rotors with smaller diameter central mounting holes, the OD of your rotors are also smaller than later bikes. It is possible to make a later wheel fit, but it is not an easy bolt-in and will require some backyard 'engineering'.

I have later wheels in my Glide, but using later fork sliders with Brembo calipers and a later swingarm, wheel and Brembo caliper, plus other related mods.