37s Load D or E?

[CrazyDrei]

Exactly how much forest road driving do you do? Do you deflate the tires from pavement to forest roads?

If you take the time to deflate your tires to appropriate surface right now and then air them back up for pavement then go with 17s and the bigger sidewall.

If you currently do not deflate the tires for different road surfaces then stay with the E rated to maximize on pavement stability.

What exactly are you looking for? If you are looking for off road comfort then go with 17" D rating if you are looking for on road performance go with E rated 18"

How much of a load do you plan on carrying and how hard do you plan on driving?

 

[MTVR]

E.

There is never an acceptable reason to downgrade a safety component.

There is no point in downgrading to a lower load range than the "E" minimum specified by Fiat, especially since you're carrying over a ton of weight in it.

Remember, there are limits to how much money your liability insurance policy will pay out, but there is no limit to the amount of money that a civil lawsuit might take from you. If someone got hurt after you modified the suspension and tires of your vehicle to reduce the braking, accident-avoidance, and load-carrying abilities of your vehicle, those downgraded tires would just give some personal injury attorney one more reason to make you homeless.

For safety, I just run the stock suspension and stock 53" tall load range M (22-ply rating) Michelin radials on our vehicle. They're rated for 14,540 pounds each, so I feel they should be adequate for us...

 

[Betarocker]

Look at the Load Index, not just the Load Range (D or E). Also, check the capacity of the rims or axle, they might not even be strong enough to handle the max load of the tire.

TOYO TIRES - Europe

Toyo Tires Official Web site

www.toyotires.com

 

[charlieaarons]

Won't clear the brakes.
Also, those would ride like hell

Re 255/100R16s:
If 16s won’t fit over the brakes, so be it. But I doubt that you have any personal experience with those tires. I do. When I replaced the stock 235/85R16s with the 255/100s on my 88 F350CC (with add-a-leafs at both ends), the ride improved greatly, as one would of course expect with more air and sidewall between wheels and ground.

 

[CodyY]

Re 255/100R16s:
If 16s won’t fit over the brakes, so be it. But I doubt that you have any personal experience with those tires. I do. When I replaced the stock 235/85R16s with the 255/100s on my 88 F350CC (with add-a-leafs at both ends), the ride improved greatly, as one would of course expect with more air and sidewall between wheels and ground.

That's awfully presumptuous of you.
I do have experience with that tire. On service trucks, as they are intended for.

And I would also say a leaf sprung, with add a leaf, 1 ton super duty is hardly the hold standard for ride quality when compared to the latest offerings from any manufacturer. So, much like the F450/550 welding trucks I used to drive the tire is least noticeable variable in the equation

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[Regcabguy]

E.

There is never an acceptable reason to downgrade a safety component.

There is no point in downgrading to a lower load range than the "E" minimum specified by Fiat, especially since you're carrying over a ton of weight in it.

Remember, there are limits to how much money your liability insurance policy will pay out, but there is no limit to the amount of money that a civil lawsuit might take from you. If someone got hurt after you modified the suspension and tires of your vehicle to reduce the braking, accident-avoidance, and load-carrying abilities of your vehicle, those downgraded tires would just give some personal injury attorney one more reason to make you homeless.

For safety, I just run the stock suspension and stock 53" tall load range M (22-ply rating) Michelin radials on our vehicle. They're rated for 14,540 pounds each, so I feel they should be adequate for us...

How much metal did you have to cut for stock suspension and 53's? I would think 53's would seriously compromise your braking unless you have manual with EB.

 

[1000arms]

... For safety, I just run the stock suspension and stock 53" tall load range M (22-ply rating) Michelin radials on our vehicle. They're rated for 14,540 pounds each, so I feel they should be adequate for us...

How much metal did you have to cut for stock suspension and 53's? I would think 53's would seriously compromise your braking unless you have manual with EB.

I recently purchased a 2007 Oshkosh MTVR. We intend to convert it into an overland expedition type vehicle and do full-time RV living.

For those not familiar with the MTVR, it is an all-terrain military 6x6 truck built for the U.S. Marine Corps, and it is...big- nearly 12 feet tall. MTVR occupants look down into 18-wheel tractor-trailer rigs on the highway. It's powered by an 11.9 liter (730 cubic inch) Caterpillar turbodiesel that puts out 425 horsepower and 1,550 pound-feet of torque. The runflat tires are 53" tall, and weigh 500 pounds each. The truck weighs about 30,000 pounds empty, and with a GVWR of 62,200 pounds, has a rated payload capacity of 30,000 pounds. It can ford five feet of water.

It's also much more sophisticated than the older/smaller 2-1/2 ton and 5-ton trucks- the MTVR has a heavy-duty 7-speed Allison double overdrive automatic transmission, a single-speed transfer case, full-time all-wheel-drive, five selectable drivetrain lockers, coil-sprung long-travel fully independent suspension, dual central tire inflation systems, beadlocks, ABS, traction control, power steering, air-ride seats, can easily do 65mph, and the late-model ones like mine even have air conditioning.

The U.S. government originally paid about $250,000 for it. After they put about 3,000 miles on it, I was able to purchase it at auction for $15,500. The tubeless Michelin radial tires still look like new.View attachment 575282View attachment 575283

One doesn't often get to honestly type "53 inch tires are the stock tires."

Maybe @MTVR also runs the stock tires and stock suspension so he won't have to chop his cab (and camper)? ...

 

[MTVR]

One doesn't often get to honestly type "53 inch tires are the stock tires."

Maybe @MTVR also runs the stock tires and stock suspension so he won't have to chop his cab (and camper)? ...

Lol, yeah. A six inch "lift kit" would put us over 14 feet tall...

 

[MTVR]

How much metal did you have to cut for stock suspension and 53's?

None. Like I said, the 53" tall tires are the stock tires. Plenty of room, even with the stock long-travel (16") fully-independent suspension.

I would think 53's would seriously compromise your braking unless you have manual with EB.

No, the stock brakes are absolutely massive, there are six of them, and the 11.9-liter (732 cubic inch) Cat turbodiesel comes stock with an automatic engine compression brake with three programmable settings. 425 horsepower and 1,550 pounds of torque helps it to get going again afterwards.

And the transmission is a heavy-duty Allison 7-speed double-overdrive automatic.

With five selectable drivetrain locks and dual CTIS systems, I don't think we'd ever need larger tires...

 

[mk216v]

We've been running 37x12.5R17 in load Range D with ~3,500 load capacity at 50psi. Run them in deep snow at 20psi. Off road @ 30-40psi. Keep the rear 5-10psi higher typically to match front sidewall deflection. Rear axle is about 6k lbs with the camper. I like running lower air pressure. Less harsh ride. No issues on road so far.

I've yet to get a solid answer about the Load to letter rating. Higher letter rating seems to have more to do with max PSI than load capacity. Load E is alway over 65psi. Load D does not exceed 50psi. I've looked at nearly every brand of tire in the 37 size. Numerous will show D or E with the same load capacity listed but higher PSI with E.

Which sidewall has to be stronger? 3,500lb load @ 50psi or 3,500lb load @ 65psi. I'd be curious to measure the sidewall thickness. It seems like you'd need a thicker sidewall to run less PSI and carry the same load.

Most important factory is enough rated load capacity to your use.

It's a lot easier airing up/down when not inflating past 50psi. But we are changing air pressure constantly and spend days at low psi off road. Dual air compressors to air up each side separately. So guess it depends on use. For hwy only rig.... go E or F with less sidewall. Best handling. Although, heavy, tall rigs and handling is a joke. Buy a car for handling.

Typically E load is 10ply, D load is 8ply.
I don't know why few if any 37" tires are made in E load vs D load (D's have a higher load rating at lower psi). Asked here, but didn't get a solid answer;

https://expeditionportal.com/forum/threads/announcing-the-overland-journal-podcast.212065/page-3#post-2843853

 

[montypower]

Typically E load is 10ply, D load is 8ply.
I don't know why few if any 37" tires are made in E load vs D load (D's have a higher load rating at lower psi). Asked here, but didn't get a solid answer;

https://expeditionportal.com/forum/threads/announcing-the-overland-journal-podcast.212065/page-3#post-2843853

Ply count was how tires were made years ago... But nothing is 10ply today. They call it "equivalent" in strength based on whatever manufacturer standards. The tire world should be revamped. Same with the sizing. It's crazy you can buy a 37" tire and have the actual diameter vary over .5" or more depending on manufacturer.

There should be a standardized system for testing each tire: diameter, thickness, load fail weight, noise, stopping distance, cornering stability, sidewall strength and more. Then consumers could actually compare products intelligently.

Tires are the topic where I find most people think whatever they have is the "best". But many have a limited experience base of tire brands, types to even know. So most reviews are not helpful.

 

[jadmt]

Ply count was how tires were made years ago... But today nothing is 10ply today. They call it "equivalent" in strength based on whatever manufacturer standards. The tire world should be revamped. Same with the sizing. It's crazy you can buy a 37" tire and have the actual diameter vary over .5" or more depending on manufacturer.

There should be a standardized system for testing each tire: diameter, thickness, load fail weight, noise, stopping distance, cornering stability, sidewall strength and more. Then consumers could actually compare products intelligently.

Tires are the topic where I find most people think whatever they have is the "best". But many have a limited experience base of tire brands, types to even know. So most reviews are not helpful.

I dunno when I look at what is stamped on my Toyo E rated side walls the plies add up to 10 plies.

 

[montypower]

Adding all the section ply counts together isn't how the ply count works.

From Tire Rack
"Today's load range/ply ratings do not count the actual number of body ply layers used to make up the tire's internal structure, but indicate an equivalent strength compared to early bias ply tires. Most radial passenger tires have one or two body plies, and light truck tires, even those with heavy-duty ratings (10-, 12- or 14-ply rated), actually have only two or three fabric plies, or one steel body ply."

Key item is load capacity rating. It doesn't hurt to run a E or F rated tire. But keep in mind, you'll need to run the specified pressure to achieve the load capacity.

So far, I've appreciated the lower 50psi rating for the ~3,500lb capacity. Much easier to live with off road to on road transitions. Might as well go overkill if your truck stays at highway pressure! (my thoughts - not advice so do with it what you want)

 

[Regcabguy]

Popup trailer or slide-in?
Just to be sure.

I'm guessing trailer. If so, it really doesn't matter. I went from Toyo Mt 37x12.5-17 D range to Falken wildpeak at3w 37x12.5-17 D2 range. Mostly for road noise and because we bought a 24 foot toyhauler.

I'm extremely impressed with the ride quality improvement and noise reduction over the MT tires. That said, I don't think you're going to be dissatisfied with the RidgeGrappler, I'm just doing more towing and road miles these days. I also picked up 1.5 mpg (but to be fair its a V10 with 5.13 gears and gets single digits most of the time anyways).
Its my shop truck and tow rig for customer cars and the camper with the family so the RG style tread wasn't really necessary for me.

My buddy has new 18" RG 35s on his super duty that are F3 rated for pulling his big camper. They needed 3x balancing over the course of 1000 miles to finally smooth out.
YMMV

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Tell him to get some Centramatics.

 

[CodyY]

Tell him to get some Centramatics.

They're fine now. I have them on mine

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