Vanilla Gorilla: 2017 Power Wagon build

[Explorerinil]

the 37x12.50R17D M/T has a load rating of 3525, the 37x13.50R20E's that i run currently have a load rating of 3860. Not a huge difference honestly.

Wait for the new Falken R/T that will be out this coming summer, its built specifically for 3/4 and one ton trucks.

I’m not going to do another RT tire, I’m after a mud terrain, I guess I’ll have to get some 37x13.50r17 Toyo MT e rated tires. Please tell flaken to make an e rated 37 on a 17 inch rim.

I don’t care about the d vs e arguments... I want an e rated tire, I feel they last longer on a heavy truck, I’ve seen that first hand.

 

[marshal]

I’m not going to do another RT tire, I’m after a mud terrain, I guess I’ll have to get some 37x13.50r17 Toyo MT e rated tires. Please tell flaken to make an e rated 37 on a 17 inch rim.

I don’t care about the d vs e arguments... I want an e rated tire, I feel they last longer on a heavy truck, I’ve seen that first hand.

you don't want the D?

generally, the manufacturers adjust the rubber compound and vulcanization based on the ply rating. In the instance of Falken, they overbuild. They wrap their ply's around the steel belt and back again. They're the only MFG to do this, which is why their tires are so damn heavy despite them running on the smaller side. This means your 3 ply D rated tires are actually 6 ply.

that said. 40K is the common limit from the wildpeak MT's in D ply on our trucks

 

[ttengineer]

Is it?

Theoretically, wouldn't you want your tire load rating to accommodate your GVWR, or close to your GVWR, with only 3 tires on the ground?

Three 37x12.5R17 Falken tires only gives you 10,575lbs of capacity, which is a bit under the 3500's 11,700lb GVWR.

Why three?

But either way, with modified suspension, most trucks are no longer capable of GVWR, nor do many drivers ever even hit GVWR.

It’s obviously one of those situations that’s going to vary from user to user, and needs to be evaluated on a individuals needs and wants. But honestly with factor of safety considerations for design, it’s not exactly irresponsible to hit 120% of load rating once in a blue moon for a short time.

I’ve done it, not often, but it’s happened.



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[ttengineer]

I’m not going to do another RT tire, I’m after a mud terrain, I guess I’ll have to get some 37x13.50r17 Toyo MT e rated tires. Please tell flaken to make an e rated 37 on a 17 inch rim.

I don’t care about the d vs e arguments... I want an e rated tire, I feel they last longer on a heavy truck, I’ve seen that first hand.

Do they though? The tires are for the most part made with the same rubber compound across the sizes and ratings. It honestly should come down to psi and footprint. If you run the same psi in a D as you do in an E, the E will obviously last longer because it’s a stiffer tire. Increase the psi in the D to match the foot print and I would be shocked if you don’t match the tread life of the E tire.

I run 30psi in the rear and 50psi out front in my 37x12.5r17 ridge grapplers when unloaded and after 2 rotations and 8,000 miles, I’ve lost less than 3/32 of tread.


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[Tex68w]

I've kept my load range D 8-ply 37x13.50x18 Toyo RT's at/around 42 PSI when on road for the life of the tires on the Power Wagon. I am at 9,000+ miles of mixed driving with them now and they've only lost 2/32 of tread. My truck weighs over 7,000 lbs and it is driven at speeds of 70-75 mph daily with an off-road mix of sand/shells on the beach and dirt/clay/mud/rock/thorns at the farm and ranch thrown in for good measure at least a few times a month.

So far I am very impressed with how these tires have held up to the abuse and the weight. Granted another 600-1000 lbs from a diesel truck might make the difference in their durability, but so far the load range D seems to be meaningless at least in my scenario.

 

[Dalko43]

Why three?

But either way, with modified suspension, most trucks are no longer capable of GVWR, nor do many drivers ever even hit GVWR.

It’s obviously one of those situations that’s going to vary from user to user, and needs to be evaluated on a individuals needs and wants. But honestly with factor of safety considerations for design, it’s not exactly irresponsible to hit 120% of load rating once in a blue moon for a short time.

I’ve done it, not often, but it’s happened.

Because when you get into terrain that causes the suspension to articulate, you may very well have 1 tire come off the ground, at which point the remaining 3 tires need to be able to support the vehicle's combined weight.

Anyways, for a Ram 2500, a 3.5k lb rated tire will be more than adequate to cover the 10k GVWR in that kind of articulation scenario. For a 3500, I'd assume that you'd want a higher-rated tire, unless you're making a conscious decision to stay well below that 11.5k GVWR.

 

[reloaderguy]

Do they though? The tires are for the most part made with the same rubber compound across the sizes and ratings. It honestly should come down to psi and footprint. If you run the same psi in a D as you do in an E, the E will obviously last longer because it’s a stiffer tire. Increase the psi in the D to match the foot print and I would be shocked if you don’t match the tread life of the E tire.

I run 30psi in the rear and 50psi out front in my 37x12.5r17 ridge grapplers when unloaded and after 2 rotations and 8,000 miles, I’ve lost less than 3/32 of tread.


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That depends on the manufacturer. The load ID is a function of air pressure. Toyo, for example, uses the same construction and materials for the 37x12.5R17 D as their 37x13.5R17 E tires. Both tires exceed the axle load rating of the vehicle.

 

[Bayou Boy]

Because when you get into terrain that causes the suspension to articulate, you may very well have 1 tire come off the ground, at which point the remaining 3 tires need to be able to support the vehicle's combined weight.

Anyways, for a Ram 2500, a 3.5k lb rated tire will be more than adequate to cover the 10k GVWR in that kind of articulation scenario. For a 3500, I'd assume that you'd want a higher-rated tire, unless you're making a conscious decision to stay well below that 11.5k GVWR.

Load capacity is specified at the max speed rating of the tire. Tires can carry more weight without overheating while crawling around. There are commercial tires that actually have different load rating at different speeds to support this.

 

[Dalko43]

Load capacity is specified at the max speed rating of the tire. Tires can carry more weight without overheating while crawling around. There are commercial tires that actually have different load rating at different speeds to support this.

Are you sure on that?

I'd always understood that the max weight rating for a given tire was the maximum weight allowed period, regardless of speed.

 

[Bayou Boy]

Are you sure on that?

I'd always understood that the max weight rating for a given tire was the maximum weight allowed period, regardless of speed.

Here you go. Page 88. While this is for truck tires the concept is sound.
https://www.michelintruck.com/assets/pdf/2010_TruckTireDataBook_jul.pdf

I'm trying to figure out why you think you can't have a wheel off the ground and have the other three tires overloaded for a few seconds. This is the first time in my entire life I have heard that.

 

[Dalko43]

Here you go. Page 88. While this is for truck tires the concept is sound.
https://www.michelintruck.com/assets/pdf/2010_TruckTireDataBook_jul.pdf

I'm trying to figure out why you think you can't have a wheel off the ground and have the other three tires overloaded for a few seconds. This is the first time in my entire life I have heard that.

I don't understand what that page is demonstrating. Are you saying that the weight rating for a given tire is intended for a certain speed, and therefore at slow speeds or stationary, the rating is inherently higher? Do the conventional A/T and M/T tires show that info? I thought the weight rating was the max weight allowed period, regardless of speed.

And you may have never heard of this issue before, but it's a perfectly logical consideration. The weight rating of the tires needs to be able to support the weight of the vehicle + additional payload (GVWR). Even if the 3 tires on the ground scenario is only momentary, you still want those tires to be able to support the weight. For a 10k GVWR vehicle (2500's, 1/2 tons) this is probably a non-issue since many available tires provide more than enough weight capacity. For 3500's or the bigger HD's, tire weight rating needs a bit more consideration.

 

[Bayou Boy]

I don't understand what that page is demonstrating. Are you saying that the weight rating for a given tire is intended for a certain speed, and therefore at slow speeds or stationary, the rating is inherently higher? Do the conventional A/T and M/T tires show that info? I thought the weight rating was the max weight allowed period, regardless of speed.

That page is showing that the allowable weight capacity is higher at lower speeds. Weight capacity and speed ratings are really heat ratings translated into things we can measure. When you think about it like that, this all makes sense. Also that table is from the TRA specifications and applies to all tires. Not just Michelin Commercial tires.

And you may have never heard of this issue before, but it's a perfectly logical consideration. The weight rating of the tires needs to be able to support the weight of the vehicle + additional payload (GVWR). Even if the 3 tires on the ground scenario is only momentary, you still want those tires to be able to support the weight. For a 10k GVWR vehicle (2500's, 1/2 tons) this is probably a non-issue since many available tires provide more than enough weight capacity. For 3500's or the bigger HD's, tire weight rating needs a bit more consideration.

There is a reason that weight ratings and speed ratings are grouped together on the tire. Like this. "128S" The rating is Load Index 128 at an S speed rating. Did you also know that you can go faster than the speed rating if you derate the load index? Because it's heat that destroys tires. Not weight nor speed. There is a lot of information in the various load manuals but they only put the relevant information in each manual for the expected use of those tires. When you put all of the data together, it all makes sense.


From page 89 of that same manual, "
The Tire and Rim Association (TRA) permits operating a 65 mph rated tire at higher speeds with a reduced load and increased inflation. No such permission is granted by TRA for tires with speed rating rated below 65 mph."

 

[Bayou Boy]

fresh tires got delivered from Falken. Going to get these AT3's mounted on the new AEV wheels for the winter

Untitled by Will Marshal, on Flickr

I'm really interested in how those AT3s work for you. I'm looking at those for my next set but they are really hard to find it seems.

 

[Dalko43]

That page is showing that the allowable weight capacity is higher at lower speeds. Weight capacity and speed ratings are really heat ratings translated into things we can measure. When you think about it like that, this all makes sense. Also that table is from the TRA specifications and applies to all tires. Not just Michelin Commercial tires.



There is a reason that weight ratings and speed ratings are grouped together on the tire. Like this. "128S" The rating is Load Index 128 at an S speed rating. Did you also know that you can go faster than the speed rating if you derate the load index? Because it's heat that destroys tires. Not weight nor speed. There is a lot of information in the various load manuals but they only put the relevant information in each manual for the expected use of those tires. When you put all of the data together, it all makes sense.


From page 89 of that same manual, "
The Tire and Rim Association (TRA) permits operating a 65 mph rated tire at higher speeds with a reduced load and increased inflation. No such permission is granted by TRA for tires with speed rating rated below 65 mph."

The wording in the PDF you provided is vague. For section A, it says "+75%" load change for creep speed, and it also says "+30 psi." Does that literally mean its safe to increase the rated tire load by 75%, because that's a vague implication and not directly stated anywhere in the manual. Moreover, are you required to increase the tire pressure in order to accept that +75% load? Because if so, that's the opposite of what you want to do for slow-speed technical crawling.

If you can find literature for the LT tires being used for Ram 2500's and 3500's which explicitly states that you're allowed to go over the weight rating at certain speeds, I'll believe it. Until then, I'm going by the weight ratings printed on the tire's sidewall.

 

[Bayou Boy]

The wording in the PDF you provided is vague. For section A, it says "+75%" load change for creep speed, and it also says "+30 psi." Does that literally mean its safe to increase the rated tire load by 75%, because that's a vague implication and not directly stated anywhere in the manual. Moreover, are you required to increase the tire pressure in order to accept that +75% load? Because if so, that's the opposite of what you want to do for slow-speed technical crawling.

If you can find literature for the LT tires being used for Ram 2500's and 3500's which explicitly states that you're allowed to go over the weight rating at certain speeds, I'll believe it. Until then, I'm going by the weight ratings printed on the tire's sidewall.

I typed a response but then realized it was pointless. Have fun running around in your new HD truck with 80psi on all corners so you can lift a tire.