| Width of Unit at Base | Number of Axles Required | Wheels w/ Brakes |
| > 8' 6" but < 10' | 2 or more | All wheels on 2 axles (a towing unit w/minimum. 9,000 GVWR all wheels on 1 axle) |
| 10' to 14' (under 60' in length) | 2 or more (3 or more if > 60' long) | All wheels on 2 axles (tires w/minimum 8:00 x 14.5, 10 ply) |