37s on a Stock Power Wagon

A minute ago, I walked through going from the stocker 33-inch Goodyear Duratracs to 35-inch Coopers. There were absolutely zero issues running 35s on a stock Power Wagon with stock wheels. And again, this won’t be a review of the Coopers (I’ve done that). But this is my fourth set and will likely be my fifth.

After a recent trip took out a sidewall of the 35s – I used my Discount Tire certificate to jump to 37s. The Internet – the authority it is – will reassure you that you can fit 37s on a stock fourth and fifth gen Ram Power Wagon with only minor sway bar rub. After running 37s for 1,000 miles – here’s been my experience.

First-off, and perhaps most importantly, 37s look great. They fill the wheel wells like they should and add some much needed stance to the truck (especially compared to when the stock 33s are aired down).

Despite the conflicting reports online – yes you do need to trim to fit 37s. The level of trimming needed depends on the offset your wheels have. Standard (Big Horn, Laramie, etc.) Rams have less offset (+57mm) on the OEM wheels than Power Wagons (+42mm). So Power Wagons will fair better here (not to mention the 2″ lift Power Wagons come with). But even the Power Wagon wheels don’t have the ideal +18-25mm offset needed to minimize rub. Plan on trimming any wheel flair (PW and Laramie trims) seams that protrude into the fender well along with 3-4″ up the fender liner. You can see in these photos – I’m still getting some rub when stuffed and turning higher up in the fender liner above where I’ve trimmed on the driver’s side.

After trimming the fender liner and touching up the paint behind – you’re good to go. Or so the doldrums of connected misinformation might have you believe (that’s the Internet in this case). Instead – especially on factory wheels – prepare for all kinds of rub at full lock. Your radius arm and sway bar will enjoy the ribbed-for-her-pleasure sidewall embrace at full lock in either direction.

So that’s the skinny on rub. No issues in the rear at all. So let’s run down the remainder of the list of things I typically cover in one of these.

Does the spare fit in the stock location?

No – not even remotely close.

CORRECTED SPEEDOMETER/ODOMETER (AEV PROCAL)

The AEV ProCal is awesome for a lot of reasons. But one of them being that you can change the tire size the truck thinks is on there. This not only adjusts your odometer and speedometer so that they’re correct — it changes your shift points. So while putting a 4″ larger tire is impossible without re-gearing; it instead feels like you’re towing an empty or light trailer instead. Note, the ProCal is dead on when set at 35.25″.

WHAT’S IT DO TO YOUR GAS MILEAGE?

It’s going to drop – no doubt. I don’t have any good data yet (my 1,000 miles have largely been met with side or tail winds). So I’ve seen as good as 17 MPG on a tank and as bad as 9 MPG. Looking like a loss of 1 MPG on the highway – and more in town.

HOW’S BRAKING?

Like with 35s, this is what’s probably changed the most. But still isn’t bad; and again, I’d say it feels like you’re pulling an empty or light trailer.

How’s the handling?

While I don’t feel like I have a final verdict – the answer won’t be “better”. I don’t feel the added comfort of more sidewall on the road – but I do feel like the truck is squish’ier (that’s a word) in the corners. Part of that is likely a higher center of gravity. And I’m sure part of it is the added sidewall. The steering in general feels busier with more road chatter than before. Whereas with 33s and 35s I had no interest in upgrading steering components – I now have my eye on a heavy-duty tie rod and upgraded damper (include a drag link there too if you haven’t already changed it after the recall). Off-road however it rolls over objects more easily (like you would anticipate) and I’ve already found I can get away with not airing down in places I would need to with 33s and 35s.

Summary

37s is definitely the tipping point where you trade drive-ability and road manners for off-road prowess and aesthetics. It’s also going to require special attention to other parts of the truck (wheels with more offset, upgrade steering components, trimming, etc.). When compared to 35s, which are bolt-on turn-key, you have to really want them. For us – I think they’re the right tire size. But unlike the internet may have you believe – I think 37s are for the minority of owners.