load rating

From: Patrick and Kelly Engram (shetland@erols.com)
Date: Tue Sep 22 1998 - 23:48:36 EDT


Please be sure that the load rating of the tire you pick is adequate for
your hauling/towing needs.

I think the lower profile tires have less load capacity.

Al"

They will have a lower load capacity if the air volume of the tire is
less than the air volume of the tire being replaced, all else being
equal. Since the air in the tire essentially dictates the load
capacity, if you go to a wider diameter tire without going taller, you
are still increasing the air volume. Add to that the fact that most
255/50R16's have an maximum inflation of 44-50 psi versus 35-44 psi for
a 235/70R15 or 215/75R15 means that the "lower profile" tire will still
hold a greater load, and may need the air pressure in the tire dropped a
few pounds to keep the tire flat on cornering and to keep it from
wearing out in the center too fast.
  The term low profile tire is used loosely to describe any tire with a
lower aspect ratio than a 70 series. But the height of the sidewall is
not dictated by this number, but by the section width of the tire and
the aspect ration. This is why a 255/50R16 is still a taller tire than
a 235/70R15 (although only by a fraction of an inch)
  You are correct in bringing up the point of load carrying capacity,
though, and I commend you on that. Frequently, people come in that want
to slam their trucks, like put a 245/50R15 or some real small tire on to
lower the truck. In almost all cases, there is no "low profile" tire
that will lower the truck but still be able to handle the weight
carrying requirements too. Besides, this really throws off the
speedometer and the alignment.
  Patrick



This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:09:56 EDT