My son bought a 2005 cr85r The rear tire needed replace so we got the same size that was on it. Turns out someone had put a larger wheel and tire on both the front and back. It takes a 90/100-14 on the rear and 70/100-17 on the front as stock but currently has 90/100-16 on the rear and 70/100-19 on the front . It was fine like this until we took off the rear tire to replace it. Got the new tire on the rim and went to put it back on and it barely got on but it won’t spin because it hits the swing arm. Wondering how come if it’s the same size as we took off it’s not working. Local bike shop says it should be the smaller tires and wheels but we’re stuck with what we’ve got. Any recommendations? How hard is it to switch back to the smaller stock tires