Specifications

'ride height' check we will do in a bit and the charts in Appendix A and B will help with this
determination.
Weight
Wait a second. Before you start throwing new springs, bags, etc. at the motorhome, have you
checked its weight? You're looking for the GAWR. At a minimum, you should be able to find
the label that gives the rating for your motorhome for the front and the rear axle. Front 4,300
lbs. and rear 7,500 lbs. is a common combination for a short chassis motorhome with a 137 inch
wheelbase. Add them up and you come up with the GVWR (Gross Vehicle Weight Rating) of
11,800 lbs for our example.
That 4,300 lbs. for the front means that each tire is expected to carry 2,150 lbs. In other words,
the front is expected to be balanced side to side. Same goes for the rear. 7,500 lbs. means that
each dual pair of tires is expected to carry 3,750 lbs. (that's 1,875 lbs. per tire). This means these
are the MAXIMUM weights at each corner of the motorhome. It was designed for these
weights. You can't simply put on a 'better' tire or overinflate the tire or airbags to compensate
for higher weight at one corner. Could be that the wheel bearings, springs or the axle are the
limiting factor and you might crunch something if you exceed a corner weight.
Anyway, get it weighed. Preferably each corner separately. You might check with your local state
police and find out if they will help. They stop large trucks on the highway and conduct random
weight checks – so they have the equipment and may be willing to help you since you are
pursuing a safety aspect of driving your coach.
Once weighed, you may find your handling problem real quick. First, you cannot exceed the
maximum for the corner. Second, you really want to be balanced side-to-side on each axle for
best handling. Move stuff around until you can achieve this. Incidentally, weigh with the same
maximum configuration that duplicates how you travel. Full fuel tank, full fresh water. If you
travel with much in the holding tanks, you should also take that into consideration and try to
duplicate it – maybe even fill them up too. Load up with all the clothes, tools, passengers, etc.
that you normally carry. Make sure you are in the driver's seat or a representative amount of
weight has been placed there. You're not going to be graded on this by anyone but yourself
(well, maybe your spouse). You may find you have to change some habits and dump tanks more
often, carry less goodies, carry less water, lose some weight.........
At this point, worn parts are taken care of and the motorhome is within weight parameters. We
are almost ready to head to the alignment shop.
Almost.
How about those tires?
http://users.sisna.com/cebula/P-Chassis-AlignmentProcess.pdf 11 Version 0.7 –Sep 14, 2005