40's vs 37's. What's the reality while daily driving?


Ya, I thought going to 35s from 32s was net positive even on the road. That was stock street tires to ATs also. Didn't even hurt MPG! Acceleration dropped a little, but it's still more than I'll ever need. And offroad bigger tires roll over bumps better, and it's the best way to increase ground clearance. Wish I'd gotten 37s.


I e got 37s on my Ram with the AEV kit. I notice zero difference in driveability.

I run 50psi up front and 30 in the rear when unloaded and that has helped tremendously in ride quality.

40s with hydro assist will probably feel even better behind the wheel because the hydro is such an improvement in handling.

Add a Carli sway bar, a synergy steering brace, and some upgraded steering components as needed and you’ll be sitting pretty.

The only issue will be parking with the wider tires and fender flares.

I’d daily mine with 40s in a heart beat if I had the extra coin laying around. And I live in Atlanta.

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Might need some info on the DD requirements. 50 miles each way on highway vs 3 miles on city streets....

Have not run 40s, but 37s for years. A big truck may not be a good commuter with either choice.

Or just do it and don’t look back. If you drive in the right lane, you can always see inside the car to the left of you. Good times if you live in a warm climate.
I went to 40's last year, I could probably DD it but that would be an expensive proposition. If I were forced to DD the truck I'd look at a 20' wheel and tire combo instead of the 17". I'm running a full Thuren kit with Kings valved for 40's, gears, hydro assist, truss, etc. The truck is only 2" taller than when it was on 37's, the major difference is the 6" of added width but it's not much different overall than when it had 37's. I have front and rear cameras so parking is pretty easy and the truck just drives exceptionally well for the tire size. If you don't mind burning up $2k+ worth of tires a year and the added fuel cost then the truck will be fine.


I have been Daily Driving my 17 XL build, no issues at all. Yeah, tires aren't cheep, milage is affected a little, a little more difficult to get in and out of but all in all, I love it. Heck I even run it on 43.25" tires on bead locks for off road use. 37s are a great size though, less stuff to change, probably more dependability in the long run with stock components. If you have the ability to get a good deal on a truck built for 40s then you aren't fronting all the build money and I think it makes it more tolerable (personally)......

AEV stuff, lift, flares, bumper, raised air intake, 4:88 gears, ARB, WARN winch, PSC steering, 20" wheels, Conti. MPTs (for road use), 42" Maxxis Treps on 17" walker evens bead locks (off road use) bunch of expo stuff.



Beach Bum
It's a tough call in my opinion. I've had quite a few trucks on 37's that I daily'd and one on 40's. I wouldn't consider the 40's without the steering upgrades, most importantly the hydraulic assist. 37's are certainly more livable, more affordable, and have less of an impact on the drive train, but both are big and heavy will more drawbacks than net positives. But in this world, bigger is better and there's no denying the cool factor of a HD truck on 40's.

Prior to selling the PW recently, 40's were my next move from 37's so I can relate. If you can swing a new set of tires every 12-18 months and you can live with all of the detractors of a truck on 40's then I say go for it, but not without addressing the steering components first. You know your commute and driving needs and your pocketbook, if they can support the move then giddy-up.
My last Ram had 37”s, now I’m on 40”s. I don’t think I’ll ever go back to 37”s on a one ton truck. The AEV Prospector XL is a perfect setup imo. Just make sure to get the hydro assist and 4.30 or lower gears. I drove 40”s for a bit with factory steering and 3.42 gears, it’s ok for the short term but I doubt a steering box would make it more than a year or two without the hydro assist.


New member
If the gearing is 4:30, you'd be better off with 35's. I run 4:56 with 35's and feel I would be better served with 4:88.


Totally different animal, not comparable. 4:30 gears work great with 37 inch or grater tires. With 4:30 gears and 37’s, I’m running 1900 rpms at 80 mph.
That is about perfect for fuel economy. I’ve found 2000 RPM to be the sweet spot.

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