Control issue
Senior Member
Joined: Dec 2003
Posts: 6,550
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From: Mount Airy,MD
http://www.falkentire.com/template.php?page=technical
From this chart, the loading looks progressive. Scroll down to the Light Truck Tire Load and Inflation Chart.
From this chart, the loading looks progressive. Scroll down to the Light Truck Tire Load and Inflation Chart.
Member
Joined: Jun 2006
Posts: 57
Likes: 1
From: Midwest
For example:
Look at LT265/70/16 single Load range E.
80/70= 1.143*(2765) =3160lbs /=/ 3415lbs shown
80/75= 1.067*(2900) = 3093 lbs /=/ 3260 lbs shown
One can not just half the pressure (80psi/40psi) and assume the capacity is halved as well. I would expect that load range e tire to have a capacity of at least 1910 lb at 35 psi with no harm done.
Look at LT265/70/16 single Load range E.
80/70= 1.143*(2765) =3160lbs /=/ 3415lbs shown
80/75= 1.067*(2900) = 3093 lbs /=/ 3260 lbs shown
One can not just half the pressure (80psi/40psi) and assume the capacity is halved as well. I would expect that load range e tire to have a capacity of at least 1910 lb at 35 psi with no harm done.
Senior Member
Joined: Dec 2003
Posts: 6,550
Likes: 2
From: Mount Airy,MD
For example:
Look at LT265/70/16 single Load range E.
80/70= 1.143*(2765) =3160lbs /=/ 3415lbs shown
80/75= 1.067*(2900) = 3093 lbs /=/ 3260 lbs shown
One can not just half the pressure (80psi/40psi) and assume the capacity is halved as well. I would expect that load range e tire to have a capacity of at least 1910 lb at 35 psi with no harm done.
Look at LT265/70/16 single Load range E.
80/70= 1.143*(2765) =3160lbs /=/ 3415lbs shown
80/75= 1.067*(2900) = 3093 lbs /=/ 3260 lbs shown
One can not just half the pressure (80psi/40psi) and assume the capacity is halved as well. I would expect that load range e tire to have a capacity of at least 1910 lb at 35 psi with no harm done.
Member
Joined: Jun 2006
Posts: 57
Likes: 1
From: Midwest
http://www.tirerack.com/tires/tirete...jsp?techid=194
Obviously I wouldn't drop below what the door jamb says but why is the capacity at 20psf not 2183/2 or appox. 1091lbs?
Additionally, while a tire's maximum load is the most weight the tire is designed to carry, its load carrying capacity at lower inflation pressures is proportional to how much inflation pressure is used. For example, P235/75R15 P-metric sized, standard load (SL) and extra load (XL) tires used on cars would be rated to carry the following loads at the inflation pressures indicated:
Air Pressure (psi) 20 23 26 29 32 35 38 41
P235/75R15 SL 1543 1635 1753 1852 1940 2028
P235/75R15 XL 1543 1635 1753 1852 1940 2028 2105 2183
Note: 35 psi is the assigned 'maximum load' pressure for standard load tires and 41 psi is the assigned 'maximum load' pressure for extra load tires.
The above chart correctly shows that an extra load tire is not rated to carry any more load than a standard load tire when both are inflated to the same pressure (up to the standard load tire's 'maximum load' pressure of 35 psi). This is because a tire's load capacity is a function of its size (which determines the size of the 'air chamber'), its construction (which determines how much pressure can be held) and the actual air pressure used (which determines how many air molecules are forced inside the chamber). All tires with equivalent physical dimensions carry equivalent loads (until they reach their maximum load pressure).
The tire's maximum load is indicated in relatively small sized print branded near the tire's bead (adjacent to the wheel) indicating the appropriate value. Because tires are global products, their maximum load capacity is branded on the tire in kilograms (kg) and pounds (lb.). These values can also be found in the industry's tire load & inflation charts.
Air Pressure (psi) 20 23 26 29 32 35 38 41
P235/75R15 SL 1543 1635 1753 1852 1940 2028
P235/75R15 XL 1543 1635 1753 1852 1940 2028 2105 2183
Note: 35 psi is the assigned 'maximum load' pressure for standard load tires and 41 psi is the assigned 'maximum load' pressure for extra load tires.
The above chart correctly shows that an extra load tire is not rated to carry any more load than a standard load tire when both are inflated to the same pressure (up to the standard load tire's 'maximum load' pressure of 35 psi). This is because a tire's load capacity is a function of its size (which determines the size of the 'air chamber'), its construction (which determines how much pressure can be held) and the actual air pressure used (which determines how many air molecules are forced inside the chamber). All tires with equivalent physical dimensions carry equivalent loads (until they reach their maximum load pressure).
The tire's maximum load is indicated in relatively small sized print branded near the tire's bead (adjacent to the wheel) indicating the appropriate value. Because tires are global products, their maximum load capacity is branded on the tire in kilograms (kg) and pounds (lb.). These values can also be found in the industry's tire load & inflation charts.
Obviously I wouldn't drop below what the door jamb says but why is the capacity at 20psf not 2183/2 or appox. 1091lbs?
Last edited by RUSTY06CREWFX4; Jul 10, 2012 at 04:07 PM. Reason: broken link
Senior Member
Joined: Dec 2003
Posts: 6,550
Likes: 2
From: Mount Airy,MD
Why are you talking about extra load, and the extra load comes in due to the higher pressures available.
As my last words, Ford would not recommend 50 psi for a LR E tire if it did not need it. All it would do is wear the tire quicker if 35 was good enough. And with a recommended of 50, the TPMS would set a fault long before it hit 35, for good reason.
Last edited by kingfish51; Jul 10, 2012 at 05:39 PM.
Member
Joined: May 2012
Posts: 79
Likes: 0
From: MN
On my last truck I'd run around 65psi when unloaded, and 80-90psi when loaded. Took a little of the rough ride out of the 3/4 ton dodge. Over 60k on one set of tires and they weren't wore out when I sold it and never had any tire problems doing that either.
