Funny you should ask. Maxis is made by Cooper, so you can shop them and find a dealer near by.
Yesterday Deb and I are on our way back from Lake Powell, when all of the sudden we get a flat (my second in a few months) on the trailer. Goodyear Marathons. Cussed the tires, took and hour and a half and got back on the road. Get just past Valley of Fire exit on I15 South and get another flat...no spare...
4.5 hours later we're on the road with 4 new maxis on the trailer....long long ride home.
btw, no issue with the tires, the problem worked out to be the trailer, the plywood carpeted guards on the fenders to protect the boat from road debris were rubbing the tires inside side wall...Kablooie...
Good luck...
Scream