Time for an inspection at a tire and alignment shop. Something has shifted that is affecting the alignment. That could be as inexpensive as a loose and shifting alignment adjustment, or as time-consuming as a broken coil spring. Some tire brands are noted for developing broken belts around the time they're worn out. That will cause a thumping in the steering wheel and can cause a pull. They will also look at ball joints, tie rod ends, and control arm bushings.