Bill:
A couple of things to know about getting a new tire from UHaul. The new ones are slightly different from the old versions, so if you plan to use wheel covers (We have an original set that went on the UHauls.), you need to find a used rim. We bought new ones, so our wheel covers are going to be repurposed.
The other thing you need to know is that not all UHaul dealerships will help you out. Ours was fine with helping us out. The dealership has to order the tire and then sell it to you. Some will not do it. In fact, one member of uhaulcamper.com was told by his UHaul dealer that all UHaul trailers were stolen, because UHaul would never sell their inventory to private citizens (Don't panic and assume that this is the case, as another member over there has the original sales slip from UHaul for his trailer. UHaul
sold them off when they became a money losing situation.) So you will need to find a willing dealer.
Hope you enjoy your UHaul as much as we do ours. We are uncovering it in a few weeks for a trip to South Dakota.
CindyL