When we took the wheels off, we had a right struggle with them. I found that if you tighten up the bolts after fitting the tyres, the wheel did not want to go back on. Slacken them off and the wheel went on easier. This is due in my opinion, that the clearance in the bolt holes allows the two halves to be a bit out. I tightened the wheel nuts up, then the bolts holding the rims together.