I have an 08 dodge ram with 17" wheels.
Ive come accross this guy who is selling the wheels and tires of a 2012 dodge ram.

The wheels are 20" wheels and the tires are 35s mud tires.
Would there be any issue? Would they fir right?

 

Which flavor truck? 1500? 2500? If you have a 1500, you are going to need some lift for 35's to fit......

 

Its a 1500. Do you know how much lift i may need?

 

I am more familiar with the second gen trucks, but, on those, the MINIMUM for 35's is about 3". 5 is what is recommended. At 3", you WILL get some rub in various places......

That said, you have independent front suspension, so, probably some differences there.