Quote:
Originally Posted by dcb
yes, but it isn't "normal" to be driving around a passenger car that weighs 8000 lbs, even in the U.S. That footprint looks underinflated/overloaded, perhaps considering that ~1/2 of cars on the road are 6psi or more below placard, it is "normal".
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Well, for one thing, the footprint in question is a for a heavy duty pickup truck - one that can have a GVW over 13K. So the load is at least appropriate for that.
Second, if I want to be able to compare footprints from different tire sizes, I should pick something that can be replicated in a different size - particularly if I have machine limitations - and in this case it was both available time on the machine and a weight limitation of 2K.
BTW, the 2 individual footprints I posted date back to around 1997.
Third, the matrix of footprints is unusual, not only because these are the same tire tested at multiple conditions, but also because none of the conditions is a "standard" condition. It has been awhile since I looked this up, but I recall the conditions match the conditions for one of the standard rolling resistance tests.
A word of caution: DO NOT take these footprints as absolutes. Footprints vary considerably - as the 2 individual footprints demonstrate. Use the footprints for trends.
And I will say this again, because it is important. The matrix of footprints is probably the best set of footprints I have seen. Most tires have considerably more variability in pressure distribution between conditions - and that leads me to suspect the tire has a cap ply (perhaps 2!)