35" vs 37" Tires

[aschafer14]

Is anyone running 35" Tires and regret not going bigger. Or running 37" tires and wish they went smaller?

We just got out super singles on order are leaning towards 35's mostly due to weight, power/gearing of the vehicle and hopefully better fitment in our FG649 (trying to avoid moving the AC condenser). Our rig currently sits at 10,500 lbs dry so I was looking at the Falken Wildpeak AT4W which have a 125R load rating (3640lbs)

 

[GR8ADV]

37 all day long. Easy cruising at 65 mph (gps actual speed) at 3k rpm.

 

[gator70]

My rig got 37s on 20 inch rims. Truck is not delivered yet. The stock tire was 31. How do I adjust the speedo, or do I use a GPS device?

 

[SkiFreak]

Given that you have a FG649, I would think that 35's would be more appropriate. That truck is definitely not a powerhouse, so 37's might make going up hills a bit more painful.
Where do you plan on taking the truck? Will it mainly stay on the blacktop or fire trails, or is your intent to go on more extreme terrain?

Just because someone says this one is better than that one is not really relevant when it comes to YOUR truck.
What you intend to do with the truck needs to be taken into account in order to make the appropriate tire choice for YOUR situation.

 

[Peter_n_Margaret]

My OKA has 305/70R19.5s with a lot less power than that FG649. Yes, it is slow up hills. I live with that. The benefits outweigh the down sides. That is the diameter it was built new with, but on 16" rims.
I would consider 37s on 20" rims a poor choice. 37s on 17" rims would be far superior.
Tyres are also part of the suspension and how well they do that part of their job is about how much wall there is and 37s on 20" is reducing that too much, in my view.
Cheers,
Peter
OKA196 motorhome

 

[mog]

I agree with @GR8ADV. I went from stock to 37/12.5-16s ( Falken Wildpeak) on my 2002 FG and it was the single best improvement. The cruising speed RPM dropped to a level where the engine was not at max RPM and normal conversations were possible in the cab. No noticeable change in 'power' as the FG was underpowered before swap, so still underpowered after. (And ya, that was a while ago when you still could get 37s in a 16 inch rim size..... now 17 is the go to rim size.)

 

[aschafer14]

@mog , Glad to hear others are running the Wildpeaks. It seems most people were referencing the Toyo MT's. but I'm looking for something that will still perform in the snow. How are they performing off road for you. Here in central Oregon we don't come across much mud.

Capability wise I'm not too worried about 35's, I have 33's on our current camping rig and haven't had any issues getting where we want to go. I know the Diff hangs lower on these but I also have huge spring under leaf packs on my Scout that hang pretty low too.

So here are the gearing calc's I did based on the numbers in the repair manual. I'm not sure if the final drive gearing is any different in the newer models but I'm going to see a big jump in cruising speed either way. I just need to weigh weather 3mph is going to be worth a hit to power and would probably net out once i hit a 1% grade.

Stock Tires


35" Tires


37" Tires