Determining Rear GAWR
I was reading another post and it got me wondering... I have a 2013 2500 HD with a rear GAWR of 6200 lbs. I have 265/70R18E Michelin's with a max load of 3525@80 psi per tire giving me a tire load cap...
Forum Discussion
BenK wrote:
another factor is the diff ring gear dia and the subsequent axle
bearing size. There are TWO 14 bolt diff's that GM puts in +8K GVWR trucks/SUVs
Note that the OEM that supplies the rear axle assembly for my GMT400
rates it at 10,000 lb GAWR
so why does GM rate it for 6,000 lb GAWR?...yes, that is the sum of
the tire's max weight rating, but does that mean if I put in 4,000 lb
rated tires it would now be rated 8,000 lb GAWR?
Mine is also the same axle assembly for the 1 ton dually of my year and it
too is rated 6,000 lb GAWR...so the exact same?
Nope, the MC bores are larger on the 1 ton dually. The rear brake drum
dia are the same, but some 8,600 GVWR Sub's have that same dia, but
2.5" wide shoes/drums...while others and the 1 ton dually has the
same dia drum, but 3.5" wide shoes/drums. The rear brake cylinder bores
are also larger. The brake proportioning valve body are also different
It's not any one component of the 'system', but the whole system that
dictates
Benk illustrates well why none of us can make assumptions about why the GVWR and axle ratings are what they are. If you just stick to what the manufacturer says is the maximum rating for each of those things you do not have to be overly concerned.
