37s Load D or E?

[Jack90]

I have a single wheel, ram 3500, with a 2,500 wet weight hallmark pop up and would like to go with 37 inch tires (already have leveling kit).

Very Windy Wyoming paved roads (gusty winds so stability is always good) and miles and miles of forest service roads with washboard (more cushion can be nice as well) is the most common.

I would like to go with a 37 x 12.5 to minimize rubbing and Nitto Ridge Grapplers.

From their website I see have two choices...

-17 inch wheel with a Load D
OR
-18 inch wheel with a Load E

Full specs of both are below.

Which one do you think I should go with?

TIRE SIZE	STOCK NUMBER	TREAD DEPTH	Overall Dia (in)Inflated Dimensions	Overall WidthInflated Dimensions	APPROVED RIM	MAXIMUM Load (lbs.) @ Press. (PSI)	WEIGHT (lbs)

37x12.50R17LT D 124Q	217050	18.3	36.77	12.52	8.5-(10.0)-11.0	3525 @ 50	81.48

37x12.50R18LT E 128Q	217260	18.3	36.77	12.52	8.5-(10.0)-11.0	3970 @ 65	83.39

 

[Grassland]

Load E.
Not like you are worried about a stuff riding tire with that kind of weight on it.

 

[billiebob]

17s for more sidewall. D/E makes no difference unless you need the E Load Capacity.

 

[BlindingWhiteTaco]

What is your actual axle load and what is the rating? The load rating for both tires is probably very close to identical at 50 PSI. The 17” will have more sidewall when aired down, but you need to know the actual axle weight/2.

 

[IdaSHO]

Go for the Load E

More stable for a given PSI, and more headroom for given weight.
This allows you to run at a lower PSI at your rolling weight more safely, for better ride, puncture resistance, and perhaps even traction.

We run a high capacity 35" Toyo (4080lbs per) on our setup.
We and loaded we are all of 12k

Summer months, we run 55-60PSI in the front, 65-70PSI in the rear.
Winter is about 10PSI less.

Off the blacktop I drop them to 35PSI or so for comfort, traction, and puncture resistance

But never have I had them all the way up to 80PSI, don't need it.
The little Viair compressor would probably hate me for it anyhow

 

[CodyY]

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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[IdaSHO]

I was assuming a slide-in

 

[McCarthy]

E for sure.

 

[CodyY]

I was assuming a slide-in

My mistake, Hallmark appears to be a slide in.
I've always referred to a "pop-up" as a little trailer with canvas sides.

So, yeah, 18s and E for sure

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[Betarocker]

My Toyo OC M/T 38x13.50R18LT D are 2910# @ 35psi, 3750# @ 50psi.

The OEM supplied E load LT265/70R17 had 2910# @ 65psi, 3195# @ 80psi.

I run the 38" MT at 35psi for normal usage and for when I add load to max capacity of the truck, I only inflate to 39psi for the rears, which equals the max load of the original tires a 80psi.

There's still plenty of rubber using am 18" rim with a 37" tire.

 

[charlieaarons]

Will the truck take 16s?
36.5” Michelin 255/100R16 XZL, 4675 lb at 80psi. 10” wide, stock 6-7” rims, if they’ll take the load.

 

[CodyY]

Will the truck take 16s?
36.5” Michelin 255/100R16 XZL, 4675 lb at 80psi. 10” wide, stock 6-7” rims, if they’ll take the load.

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

My buddy's truck has the F rated 35x12.50-18 Ridge Grappler 3970# max load

https://www.4wheelparts.com/p/nitto-35x12-50r18lt-tire-ridge-grappler-217-130/_/R-DLDT-217-130

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[Trixxx]

If I had such a heavy load, i’d definitely go with an E. I just got my first set of D tires (Toyo MT - haven’t installed them yet) but I am also only at around 1250 total payload with my trailer hooked up. Any load at 2k+ I’d have E in a heartbeat.

 

[D45]

I ran 37s on my old Ram, that were Load E.........tires were very stable and weighed a ton

The tires were also 20", so they did ride a tad rough and the sidewalls were were stiff

 

[montypower]

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.