RV Chassis Terms

Dual Wheels.

Dual wheels (commonly called Duals) simply refers to an axle where there are two tires on each side instead of only one. Almost all large trucks and motorhomes on the highway have dual wheels on their rear drive axles.

Tandem Axles.

The term Tandem Axles refers to the situation where a vehicle has two axles, one behind the other. Tandem axles on trailers usually have only a single wheel on each side of the axle. Tandem axles (and sometimes triple axles) are seen on most larger travel trailers and almost all 5th wheel trailers.

Tag Axle.

A Tag Axle is a “helper” axle meant to carry loads higher than what the chassis could safely carry with only a single rear axle. Most tag axles have single wheels on each side and are located behind the dual drive wheels of most motorhomes. You see tag axles on both old and new motorhomes, especially those which are longer and heavier.

Narrow Body. The term “narrow body” refers to older Class A motorhomes that were built on the older Dodge, Ford, or Chevy chassis, usually before 1995. A narrow body coach has an outside width of 8 feet (96").

Wide Body. The term “wide body” refers to coaches made, generally after 1997, on the newer Ford and Chevy chassis. A wide body coach has an outside width of 8 feet 6 inches (102"). (Six inches doesn’t seem like a lot, but the RV manufacturers have been able to do wonders on coach interiors with the wider body style.)