Quote:
Originally Posted by Old Tele man
...the Gross Vechicle Weight Rating (GVWR) on the door sticker of my '09 Vibe is 3860 lbs, so I did a little 'number crunching' to see how close the other numbers related to that value:
1) door sticker tire pressure = 32 psi, front and rear
2) tire sidewall "maximum" air pressure = 44 psi
3) tire 'load index' value = 89, which equates to 1279 lbs at maximum air pressure
4) so: (32psi / 44 psi)*(1279lbs / tire)*(4 tires) = 3720 lbs
5) that's 96% of GVWR, ie: (3720lbs / 3860 lbs) = 0.96
6) looks "close enuf" for decent approximation!
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A couple of comments:
For item #4: The "rated pressure" is 35 psi, not 44 - and the load is NOT proportional to the inflation pressure.
The actual load carrying capacity of a P205/55R16 89H at 32 psi is 1157# (for a grand total of 4628#) or the tires at GVW (assuming all 4 tires carry the same load when the vehicle is fully loaded!) is 83% of the GVW.
The way it was calculated in the quote should be raised some questions as the estimated load carrying capacity of the tires would be LESS than the GVW.