When I briefly towed professionally I picked up a brand new Arctic Fox from their factory and to be shipped to a Dealer customer in Fairfield, CA. At the factory in La Grande, OR I hitched it up late in the day, checked the torque (all needed tightening) and air (all needed air) then drove to Biggs Junction, OR 162 miles via I-84 to spend the night. It was a tough tow in that it was a 20mph to 30 mph headwind the whole way coming off the beautiful Columbia River. The trailer handled well since it a lightweight trailer and had a very sloped front design.
Then the very next morning the rear driver's Marathon had an all too familiar bump! Ah crap, a Marathon ST235/80E. But this is brand new tire and I'm not driving over 60 mph (probably the only professional who stayed under 65). When I called into the main office for consultation and recommendation, they confirmed to "change the tire from the spare and save the spare" which I had already done. I asked back, "I have 600 miles more to go, what about a spare since one had already developed a bulge?" and few more minutes of waiting, then my supervisor reported back, "Northwood says this is the first problem they've ever seen so drive on without one". Reluctantly that's what I did. I drove the 600 miles, finished the delivery with no spare and the receiving dealer thanking me for the trailer, and signed things off knowing they'd be getting a new replacement from Goodyear. Got paid per the plan and nothing for changing the tire since I didn't spend anything since I did the tire change myself. Well, lucky for me I had the wrenches, jacks, compressors and all the tool changing stuff but it's part of the job.
Note this is much lighter travel trailer and uses the same size tire our larger heavier fiver. It might work well in some places. Sure seems to match DQDick's reserve capacity comments.
