17x10.5

I'm looking to buy a set of 17x10.5 FR500's for the rear and 17x9 for the front.

Do I have to worry about any rubbing?

Also what is the widest tires i can put on 9 and 10.5in?

You don't have to worry about any rubbing with a 10.5" wheel. The widest tire you can go with is a 315 before you start running into any rubbing issues with the exhaust.

17x9 i have 275s on front, maxxas something tires
17x10.5 i have 315s on back no rubbing, sumitomo htrz tires

I run 315 555R's on my 10.5's with no issues. I am on pro kit springs as well

Same here with the 315's and I have the H&R SS Kit.

Also watch your quad shock, if you want to go bigger than 315. They are tapered from factory the thick end is toward the rear of the car and of your wanting to run a 335 you flip it to where the narrow end is toward the rear and the thick end closet to the caliper and rotar.