When we bought our 5488 it had 20.8x38 bias ply tires and mismatched duals with rice tires (tractor came up from the south) so we upgraded to 18.4x42 tires. The inside tires on the tractor were still pretty good tread so our dealer gave us something for them but I'm thinking trading our four old tires and rims for two new step up rims and two new 10 bolt dual rims plus four new Firestone 3 star radial tires was around $3,500. I think the 42" tires have alot more traction than 38"s plus they give you more crop clearance and a little faster road speed.