Powerdude wrote:
GVWR is a totally made up number, and it only serves a regulatory need, depending on whatever market niche the manufacturer wants to fill, and what paperwork has been filed with regulatory agencies, nothing more.
Case in point, my 2016 F250.
Front axle WR: 5200 lbs
Rear axle WR: 6100 lbs
Tire ratings: 3450 per tire (2 tires per axle adding up to 7900)
GVWR is 10,000 lbs. What combination of the above numbers adds up to 10,000 lbs ? (Hint: using regular math, no imaginary numbers, or multiple dimensions)...
I can't register it for 10,000 lbs in my state, I can only do either 8000 lbs, or 12000 lbs, no other options. I asked the lady at the DMV what would happen if I registered it for 8k, but I was found overweight. She said I'd get a ticket.
Guess which one I registered it for? :)
First, as an engineer, I want the max tire load to be greater than the GAWR (Gross Axle Weight Rating). Otherwise, I am saying the tires are not capable of handling the designed load on the axle.
Further, I know that there is side to side weight variation, and i want to account for that.
In this case, 2 X 3305# = 6610 which is greater than either 6100# or 5200# (I'll bet the pressure on the front axle is lower than the rear axles, so the tire's load carrying capacity would be lower, too!)
Further, I want the GAWR's to be larger than the GVWR (Gross Vehicle Weight Rating) because I know that the loads are never evenly distributed front to rear.
So not only should these things
NOT add up, if they did, you would know the engineer didn't understand design principles.