35s on a Power Wagon

Yeti recently got some new shoes. 315/70R17 Cooper ST/Maxx tires. A tire I’ve reviewed before (my third set) that measures 34.67″ according to Cooper. Or as the sidewall states, is Cooper’s 35×12.5.

The intention here is to answer and put to bed the FAQs of running 35s on your Heavy Duty Ram.

Does the spare fit in the stock location?

Yes. Barely. The tire sits against the hitch and smashes the wiring loom attached there and barely clears the 3-link behind the axle. And that’s at 30 PSI or less.

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 2″ larger tire usually kills a vehicle without re-gearing… it’s honestly pretty tough to tell on the Power Wagon with it reprogrammed. It holds 85 MPH just like it did with the stocker 33s. Also worth noting that for 315/70R17 – the ProCal is dead on when set at 33.25″.

What’s it do to your gas mileage?

In town, it’s looking like a loss of .25-.50 MPG. On the highway, there appears to be no difference under 70 MPH. Over 70 MPH, where the truck with the camper would struggle to hold 80 MPH with the slide-in camper, now holds it just fine and averages about 2 MPG better on average (lower RPM at the same speed). That number comes from comparing two separate trips across I-80 of more than 900 miles each. Note that the Power Wagons come with 4.10 gearing. This might not be the case for those with the Hemi and smaller gears or the Cummins.

How’s braking?

This is what’s probably changed the most. But honestly, it’s not bad. There’s a big difference between adding this rolling weight to a heavy-duty truck and something a lot smaller like a Jeep or 4Runner. While there is still a degradation — it’s incredibly minimal. And like I said, this is the biggest change in drivability. In other words, what are you waiting for?

Does it look cool?

Hell yeah.