Anyone using a tow dolly, expecially MasterTow, need to pull the grease cap and check the tightness of the spindle nut and also check the bearings. I added wheel bearing grease using the "Bearing Buddies" as the owner's manual advised to do, as i've only put about 3,000 miles on it.
Here is what happen to me Sunday, on the way back from Florida going to New Jersey;
I was towing a car on a Mastertow tow dolly (with brakes) behind my class A, northbound on Route 695 by Baltimore Md. We had just gone over the Francis Scott Key bridge when I heard a loud screetching sound behind us. I looked in my side mirror and saw the left tire of the dolly, rolling down the road, strike the center cement divider, than it rolled to the right shoulder. THANK GOD, it didn't hit anyone! We pulled over, removed the towed car and had to have a tow service remove the dolly. It now appears that the bearings heated up and failed, causing the spindle to heat up very hot and the threads to fail and spindle nut to come off!
Don't let the same happen to you; many of your trailers and tow dollies use the same cheap foreign made bearings! Check your bearings regularlly!