Assuming the tires are the same brand with the same mileage, there is likely uneven wear caused by improper front end alignment or front end wear - or one of the tires is bad.

Put the rear tires on the front and vice/versa - see what happens. If the rear tires have been on the rear of the vehicle for a while, odds are that the wear is even and you'll see if that stops the pulling/wandering.

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum