regarding weight reduction with LT tires ?
That is the misunderstanding .
The ST scale is so weak that the placard on the side of equivalent size tires shows the ST tire at a higher weight rating than the similar sized LT tire .
even though the LT tire is more tire from the same manufacuter.
The LT Tire definitely is more tire than than the same size ST tire .
from the tire rack website here is a comparison between ( nearly ) identical 235/80R16E tires :
From the tirerack website .
Goodyear ST 235/80 R 16 E
price = $ 135 each
weight = 34 # each
section width is 9.2 "
tread width= 6.8 "
diameter is 30.7 "
rated 3420 # at 80 psi on ST scale
Goodyear LT 235/85 R 16 E
price = $ 157 each
weight = 50 # each
section width is 9.3 "
tread width= 7.0 "
diameter is 31.7 "
rated 3042 # at 80 psi on LT scale
So the Goodyear ST tire is rated for 112.4 % higher load rating than the equivalent Goodyear LT tire .
And they will sell this ST tire for only 86 % of the LT tire .
And the ST tire has less mass for cordage , plys , caps and so forth because it weighs 76 % of the Goodyear LT tire .
This is very telling as to how much lower the ST standards are in relation to the LT standards .
Further the ST tire has plainly stamped on the sidewall " for trailer use only " .
The LT tire has no disclaimer .
to recap :
the manufacturer is the same.
both tires are 235 ( one is 80 = 80% and the other is 85 = 85% )
both tires are load range E or 80 PSI .
The ST tire is cheaper ( 86% cost ) .
The ST tire has less rubber and cords .
The ST tire weighs 76 % of the LT Tire .
The LT tire only gets a 3042# rating on the LT scale .
The cheaper / lighter ST tire gets a 3402 # rating on the less demanding ST scale .
This is very clear .
Goodyear , the manufacturer , has to build a much tougher tire for LT use such as on our heavy duty pickups .
