Urban Treadz tires on Evolve AT Hubs

They fit easily enough, although I had to goof a bit to get the Evolve 7" inner tubes into the Trampa Urban Treadz 6 1/2" tires without getting them pinched between the two halves of the hubs.. The tires are rated to 85 psi while the stock Evolve's are 50 psi. If you have done this before, or something similar, what pressure did you use? I started at 50 psi and have been increasing 5 psi each time out, at 65 psi on last ride. So far the Urban Treadz roll better than the stock Evolve and feel tighter in sustained turns. I'd like to go to 85 psi but don't know if I will crush the hubs.