Questions about running 35s on the PW.

[Crusty old shellback]

This is the most over-thought thing that comes up every week

It’s about a 4% change to go up from a factory tire to a typical 35x12.50 tire (~34.6”) even if you get the largest 35” (285/75-18 or ~35.4”) it’s right at a 6% change just do it and don’t worry about it.

Not necessarily true. While the tire size may only go up 6%, it does affect the overall gear ratio, which will affect other things.

I have experienced it with going from 33" tires to 35" tire then to 37" tires, all on the same truck with all other variables being equal. I plan on using the truck to haul heavy loads in the bed as well as pull a trailer. If going to the 35"s is going to affect my pulling when going up hills, then its a concern for me. Been there, done that.

 

[Rockcrawlindude]

Not necessarily true. While the tire size may only go up 6%, it does affect the overall gear ratio, which will affect other things.

I have experienced it with going from 33" tires to 35" tire then to 37" tires, all on the same truck with all other variables being equal. I plan on using the truck to haul heavy loads in the bed as well as pull a trailer. If going to the 35"s is going to affect my pulling when going up hills, then its a concern for me. Been there, done that.

Well, allow me to retort. If you already know the answer, why did you ask the question?

 

[Crusty old shellback]

I asked the question in reference to the PW with 410 HP and 8 spd to see what owners real world experience is.

My testing was done with a 300HP 4 spd. and 4.10 gears on 33s/35s/37s.

My current F250 is a 420 HP and 4sd but has 4.30 gears and 33s

So the 8spd can make a difference in how well the PW handles running 35's and 4.10 gears when hauling/towing.

The 300 HP and 37's had major issues pulling a 24 ft Toy Hauler thru the mountains.
The F250 did not,

 

[Rockcrawlindude]

33 -> 35 = ~6% difference
33 -> 37 = ~12% difference.

4.10 with 6% less mechanical advantage = ~3.87:1 effective gear ratio

4.10 with 12% less mechanical advantage = ~3.66:1 effective gear ratio.

8hp75 first gear 5:1 final gear .64:1

look up the specs on your 4 speeds.

Calculate out your RPM at any given speed and plot that into the torque curve of the engine.

 

[Crusty old shellback]

Chevy is 700r4. 3.06 1st. .70 4th.
But has less torque than the 6.4. That's the one now running 37s.
F250 has similar tq numbers as the 6.4. It's a 6.8 V10. 2.71 1st. .71 4th. But it's running 33s.
So the PW has a deeper 1st to help off the line and a higher OD to help with MPG.
Just looking for real world impressions

 

[LateToTheParty]

All numbers aside there should be zero issues running 35s on the PW.

With 37s on my old 4th gen with 3.73s, I had zero issues towing up and down the Colorado mountains. Haven't pulled more than ~5500lbs with my 4.5 gen with 37s and 4.10s, but with the 8 speed I'm sure it'll do just fine once we get to camping season, and I'm sure it would have tolerated 35s even more.

 

[Crusty old shellback]

Thanks.
I ran a K5 blazer with 3.73 and 35s. But the motor was pushing 475 Tq. So it had the power to turn the 35s on 3.73s.
Knowing how I'll use the truck, was just a little concerned on going to 35s.