So I bought a used Mavic CXP22 wheelset. Came with Conti Ultra Sport - front 25c should be okay.

But the back is 28c and rubbing up against my frame. I threw on a ACS 18t freewheel and that might be causing it to rub.

I have the stock Stripper brakes on front and back.

Should I get a new rear tire(tires are almost brand new) or increase the chain length?