Tires: Load Range vs Weight Capacity

[bajajoaquin]

I'm looking at new tires for my F350, and I've noticed that larger tires may have a lower load range, but an equal or higher rated weight capacity.

For example, my stock size is 265/75 R 16 load range E, capacity 3415 lbs. I'm looking at 285/75 R 16 load range E, with a capacity of 3550 lbs. Then the 295/75 R 16 load range D has 3415 lbs.

The main difference is that the 265 and 285 Es are rated at 80 PSI and the 295 D is rated at 60 PSI.

I put in this same question to the folks at the Tire Rack but I'll put it here, too:

What's the correlation between load range and weight rating?

 

[78Bronco]

Ply ratings...

Load Range D = 8
Load Range E = 10

The load range D tires may be fine in capacity but you will find the carcass is weaker and causes squirly driving when you are loaded to the nuts. One tire can be inflated to 80 psi and the other 60 so naturally one will be stiffer when inflated to maximum pressure. If you frequently haul at or near max capacity or tow you will want the Load Range E.

My $0.03 worth

 

[fifthcircle]

Tell me if my math is totally crazy here...

The tire sizes are also different, so that means you will have more surface on the ground with the larger tires. The 265's have 10.5" wide x 10.5" long contact patch(estimate) = 10.5 square inches on the ground. 295's will have 11.5" wide x 11.5" long(estimate) = 11.5 square inches. So with more actual surface area on the ground with the larger (wider) tire, you can go to a lower pressure and load rating (or ply rating) and carry the same weight with a larger tire.

Extreme example, a bicycle tire on my road bike that is only 1" wide has to have 130psi to carry 110lbs(per tire), but a car tire that is quite wide will only need 30psi to carry 800+lbs (per tire).

I would get the cheaper ones :ylsmoke:

 

[SChandler]

Tell me if my math is totally crazy here...

The tire sizes are also different, so that means you will have more surface on the ground with the larger tires. The 265's have 10.5" wide x 10.5" long contact patch(estimate) = 10.5 square inches on the ground. 295's will have 11.5" wide x 11.5" long(estimate) = 11.5 square inches. So with more actual surface area on the ground with the larger (wider) tire, you can go to a lower pressure and load rating (or ply rating) and carry the same weight with a larger tire.

Extreme example, a bicycle tire on my road bike that is only 1" wide has to have 130psi to carry 110lbs(per tire), but a car tire that is quite wide will only need 30psi to carry 800+lbs (per tire).

I would get the cheaper ones :ylsmoke:

Your math is crazy. If the contact patch is 10.5" x 10.5", that equals 110.25 sq. inches (assuming a square patch for simplicity), not 10.5 sq. inches. 11.5"x11.5" equals 132.25 sq. inches. You are right that a larger tire can support more weight with lower pressures, but that ignores the construction of the tire. For instance, Toyo MT's come in a 285/75R16 and a 305/70R16. Essentially the same height, the 305 is almost an inch wider. Both are load range E. The 305 is rated to carry 3525lbs and the 285 is rated to carry 3740lbs, so wider or taller doesn't necessarily mean a greater ability to carry weight.

The major difference between load range E and D is, as 78Bronco said, sidewall stiffness. If you tow or carry large loads, you will find the truck less squirly with E-rated tires than with D-rated tires for similarly sized tires.

 

[bajajoaquin]

Something like that. I'm actually considering the larger tires, because I do a lot of driving on sand, so the contact patch issue makes a difference to me. I also don't see a lot of articulation scenarios, so I'm trying to maximize the tire size I can squeeze in with no lift.

The comment about being squirrley is food for thought, though. Since the whole point of my truck is to haul a lot of crap -- uh, I mean strictly necessary equipment -- to camp.

I'll see what Tire Rack says when they get back to me.

 

[strider3700]

My local shop would not install a D range tire on my 350 if I had bought it. They had zero issue with changing size larger or smaller but wouldn't lower the load range.

 

[fifthcircle]

Yeah... 2" x 2" = 4sq". I actually had the larger numbers down, but for some reason it didn't look right to me. :drool:

LOL!!!

 

[FishPOET]

I'm looking at new tires for my F350, and I've noticed that larger tires may have a lower load range, but an equal or higher rated weight capacity.

What's the correlation between load range and weight rating?

Weight ratings are based on the volume of air that a tire can hold. The more air a tire can hold the higher the weight rating.

 

[bobcat charlie]

FLY IN THE OINTMENT!

A/O 9/1/10 those of us in California are under a new CARB regularation: Any licensed establishment (tire dealer, repair shop, or smog station) MUST inflate your tires to the levels specified on the door sticker.

If you have a 3/4 ton truck, the door sticker will be for load range E, and will specify 60psi or 70psi front, and 70psi rear.

Totally ignores load capacity. My '03 Dodge came with 265/70X17 with an E range tire load rating of 3195# at 70#psi; I've run 315/70X17 BFG AT's, load range D, with a load rating of 3195# but at 50psi! My dealer here in California can't sell me the 315/70X17 BFG AT's because he can't inflate them to 70psi!!!

Just be aware, more stupid government intrusion...

 

[Redline]

That sucks, and a CARB regulation, not a 'law'.

I hope that doesn't creep over the state line someday!

FLY IN THE OINTMENT!

A/O 9/1/10 those of us in California are under a new CARB regularation: Any licensed establishment (tire dealer, repair shop, or smog station) MUST inflate your tires to the levels specified on the door sticker.

If you have a 3/4 ton truck, the door sticker will be for load range E, and will specify 60psi or 70psi front, and 70psi rear.

Totally ignores load capacity. My '03 Dodge came with 265/70X17 with an E range tire load rating of 3195# at 70#psi; I've run 315/70X17 BFG AT's, load range D, with a load rating of 3195# but at 50psi! My dealer here in California can't sell me the 315/70X17 BFG AT's because he can't inflate them to 70psi!!!

Just be aware, more stupid government intrusion...

 

[fifthcircle]

My dealer here in California can't sell me the 315/70X17 BFG AT's because he can't inflate them to 70psi!!!

Just be aware, more stupid government intrusion...

Can you take your wheels in, off the truck, and have them mounted. Just tell them they are spares for several trailers in your fleet.... :ylsmoke:

 

[alosix]

FLY IN THE OINTMENT!

A/O 9/1/10 those of us in California are under a new CARB regularation: Any licensed establishment (tire dealer, repair shop, or smog station) MUST inflate your tires to the levels specified on the door sticker.

If you have a 3/4 ton truck, the door sticker will be for load range E, and will specify 60psi or 70psi front, and 70psi rear.

Totally ignores load capacity. My '03 Dodge came with 265/70X17 with an E range tire load rating of 3195# at 70#psi; I've run 315/70X17 BFG AT's, load range D, with a load rating of 3195# but at 50psi! My dealer here in California can't sell me the 315/70X17 BFG AT's because he can't inflate them to 70psi!!!

Just be aware, more stupid government intrusion...

Wonder if I'll even be allowed tires for my M725 here?

I wonder if voting for prop 23 would pull this back?

 

[bobcat charlie]

This is the CARB regulation requiring max tire pressure:
New section 95550 in the new subarticle 8 of article 4, subchapter 10,
chapter 1, division 3, title 17, California Code of Regulations, effective 9/1/10.

Yes, Prop 23 suspends AB32. AB32 is specifically stated as the authorization for this stupid regulation.

Right now it looks like we will end up with Jerry Brown and no on Prop 23...we are doomed! GET OUT WHILE YOU CAN!!!!

 

[JohnMcD348]

Correct me if I'm wrong but without going into all the math, the larger tires typically require less PSI/weight and the reason behind the ply rating is mainly for sidewall stability which is needed for carrying large loads.

On my 08 Ram Megacab, I have 265/70(75?) 17 tires load rated E. I keep them inflated to max which is 70psi for economy purposes. If I look at the same tire in different sizes, they all have different load/capacity ratings along with different PSI requirements.

I can remember when I was a boy back in the 70's going to see a Monster Truck water race, back when they were still real trucks and not rail frames with motors, and those Huge tires only needing about 16PSI and they were hard as rocks. Also, they created enough bouncy that they actually floated those big trucks and acted like paddles. I remember it was over around Cypress Gardens and it was a race between Big Foot and Ms All American.

 

[Regcabguy]

I'm looking at new tires for my F350, and I've noticed that larger tires may have a lower load range, but an equal or higher rated weight capacity.

For example, my stock size is 265/75 R 16 load range E, capacity 3415 lbs. I'm looking at 285/75 R 16 load range E, with a capacity of 3550 lbs. Then the 295/75 R 16 load range D has 3415 lbs.

The main difference is that the 265 and 285 Es are rated at 80 PSI and the 295 D is rated at 60 PSI.

I put in this same question to the folks at the Tire Rack but I'll put it here, too:

What's the correlation between load range and weight rating?

With your big Ford and the Callen,I can't recommend enough the need for a tough, E-rated tire. Toyo makes a 315-75-16 MT. Insanely good flat resistance and a 3800#+ load capacity. It would take a 8.5-9.0" wide rim to accomodate these though. If you go to a 17" rim,it opens up the Toyo 285-75-17 AT or MT. I'm running the AT with great results. The last thing anyone needs is a flat or a blowout on a fullsize truck. I've experienced both w/Bridgestone AT's. The Toyos have been perfect.