No way. You need an E rated tire, those D's are gonna be squishy and not so fun when you tow.

 

I know folks who pull with them on 17 and 18 inch rims and haven't seen issues. You also need to look at the load rating of the rim. Most rims (included such like Innov8 expensive forge rims) top out at 3600lbs.

And seems like you're not pulling a huge load anyways.

 

 

Why? I'm towing now with an F150 on stock A/S tires, so moving to a 37" MT on a S/D is going to be worlds different any way.. Fully inflated, they support 7,000 lbs/axle. That's in line with the stock Ford wheels as noted above; aftermarket wheels are rated at 3600 lbs.

See above...wheels rated at 3600 lbs. Right now we have a 26' TT weighing in around 5-5.5k lbs. Looking to upgrade to a 35-38' TT weighting around 8500 dry and up to 10-10.5k fully loaded (we don't add more than a few hundred pounds of gear/stuff).

 

I wouldn't worry about the wheels, I'd worry about the sidewall stiffness. A D rated tire is going to be a lot squishier than an E rated. But hey, don't listen to me, go for it, you're not going to enjoy towing with it, no matter what the specs say. You're doubling your trailer weight and almost doubling your truck weight over your F150. A D rated tire is for a 1/2 ton truck.

 

Tricon is right. Go E without second thought. The problem with 35's and 37's is lower payload and if you end up in an accident and they can determine you are under "tired" for your load and it had anything to do with the incident you won't like the financial outcome.

Play it safe and stick with something E rated.

 

don't ask a question if you're not really ready for an answer that does not line up with your rationale.
Nothing more aggravating to me then those Tundra nuts rationalizing how they pull a 10k+ 5'vr with air bags yad yada yada.....
Same mindset here.
F-350 with its ratings are to be supported with E load range tires to meet those GVWR ratings.
Anything less and you are placing many others not just you and your family at risk.
A squishy ride would be the least of your problems.

However, it's your life and money. Hope I never drive anywhere near you.

 

It's nice to know virtue signalling and gross mis-assumptions aren't limited to other parts of the internet.

You'll notice my response to Tricon was to ask if "feel" was the primary reason. If so, that's a subjective issue.

Now, if ~3600 lbs is too low for GVWR/RAGWR or any other objective issue, that's fine and that is the information I was looking for. SDcrewzer pointed out the stock wheels are only rated for ~3600 lbs, so I kept asking what was the real issue. Speaking of, how can Ford not get away with that if its a major (someone said legal) issue?

You'll note that I never argued with anyone or gave any suggestion I was here for confirmation bias. I just want to understand the reasons (i.e. facts) without all the emotional baggage from people who can't help but read a post and then insert their own assumptions.

 

From scanning Toyo's produce into page, it seems like the metric sizes tend (on average) to have a higher load rating for a particular "size" than the 37x and 35x. Is that on purpose? Just wondering if the lower ratings are an engineering thing or a market thing, simply because a lot of offroaders seem to gravitate toward tires with a two-digit height size. Completely anecdotal based on looking at one tire, but it did jump out at me.

 

Just go with the 20" Toyo's they are "E" rated.......

 

I run F rated 35x13.50-20. It can be done with 20's. Ride is very nice as well...

 

 

One of the local 4WP guys we deal with also suggested 20" wheels. I was hoping for a lower cost for 18s and a slightly improved ride, even though I like the look of the 20s as well, but don't want to create unnecessary risk. But here's where it gets confusing again...

37x13.5x18LT - load rating D, 3525 lbs max load (the tire I listed first)
37x12.5x18LT - load rating E, 3415 lbs max load

I thought Es always had a higher load limit than Ds, but that doesn't seem to be the case. They also make that same 37x12.5 tire in an F rating @ 3970 lbs, so dropping from a 13.5" wide to a 12.5" wide would also seem to do the trick. I'm just confused at how the smaller E tire supports less than the wider D.

But you're right though - going to a 20" rim size shortens the sidewall enough that they are all E or F rated. I did some quick poking around 4WPs site looking at other 37" tires of various rim sizes, and I'm not particularly thrilled with the choices (I know they're not the only place to get them, but it gives me some idea of how many options I'm like to have for a certain size). If memory serves, speccing 18" vs. 20" on the Stage 3 site as an example was around $700-ish in difference.

 

Thanks for the feedback! Do you have any pics?

THANK YOU! That was confusing the hell out of me. I'm still confused about the weight rating on stock S/D wheels, but since I won't keep them its a non-issue not worth pursuing. I think its pretty clear the 20s are the better choice if I want to stay with the Toyo MTs. Thanks fellas, I knew someone knew the right answers!