> There aren't many trucks with tires as small as a 10' trailer's!

Many Fords have the 5 x 4.5 and/or P235/75r15 on them. Which happens to be what you find on many Rangers and Bronco IIs. So, my little trailer does fine with my little Bronco II sharing the same spare. I have a spare for the trailer too, but, don't take it for short local trips. FWIW I would never tow a trailer with (2) ATVs behind the B2.