Hi all. I tried searching and am not finding the right answers... (have some layover time in LAX on the way home - redeye = suck)

Its time for new wheels and tires for the truck (happens to be an 03 Ex, but I am posting here since the topic is general and I think there are more data points available across all superduties). I am going to ~35" tire and I tow a 31' TT. I already know that the taller tire is going to be worse than a stock tire.... so no need to go there.

What I want to know is...... can anyone give direct experience in comparing the same or a very similar tire in a 16" wheel and up to an 18" wheel?

My mind says of course the shorter side-wall will be more stable under load given the same tire. But I wonder if anyone notices that in the real world. Am I wasting my time looking for tires in the size I want that are 18", or will I not see the difference and should keep my options open down to 16" (which are more available in multiple sizes and cheaper).

Thoughts are appreciated. Thanks all.

 

First you have to clarify what you understand as bigger wheels?
Common rule on cars is that when you install bigger wheels, than you get a tire with lower height to match the diameter.
Meaning 50 high tire mounted on 18" rim will give about the same size wheel what 70 high tire on 16".
50 high tire theoretically have less flex on the sides, but that more depends on the design of the tire and its rating. Higher rated tires have thicker sides, therefore less flex. Meaning no straight forward answer.
I spend small fortune on big rims for my cars only to discover that lower profile tires on bumpy California roads are major cost of headaches and actually sold one of the SUV, because my wife couldn't ride in it.
So bigger choice of sizes and cheaper price -combined with better ride comfort would bye my decision. Fancy looks can't bee seen from the cabin at 75 mph.

 

Why didn't you just put the OEM wheels back on? Sell the vehicle when it is the wheels that are the problem? That doesn't seem like a logical solution.

 

While I can't comment directly on the specific application that you are referring to, I have had some experience with this. On my old truck (2005 F150 FX4) I had 35x12.5 BFG Mud Terrains installed on the stock 18" wheels for winter driving. For summer driving I had 35x13 Nitto Terra Grapplers mounted on 22"x9 aftermarket wheels. I did notice an improvement in stability when towing with the 22s as compared to the stock 18s. That said, this was a considerable jump in wheel size compared to what you are referring to.

Now, as another comparison point, I traded the F150 in on my current truck, a 2004 Super Duty 4x4. I have been towing my pulling truck (~9000lbs gross) around all summer long with 35x12.5 Hankook Mud Terrains mounted on stock 16" wheels, and it has handled the weight much better than my F150 ever did even with the 22s on it. I really don't think you will see that much of an improvement in stability in a 16" wheel as compared to an 18", as long as you get tires that are properly rated for towing (load range E necessary) and inflated properly. If you are going to 18s based solely on improved towing stability, it isn't worth the extra expense. But if you want to go to larger wheels for the looks, then you will gain a slight improvement in stability if all other factors are equal.

 

Stability while towing doesn't come from larger tires or wheels. Stability comes from have sidewalls that do not flex as much or from a wider footprint at the towing axle (like a DRW).

Note, the added stability of a stiffer sidewall may be detrimental to your ride comfort. A lot of the perceived suspension softness or harshness is actually the tire sidewall flex.

 

For the record, I tow with 315/75-16 BFG A/T K0's and find the handling to be quite acceptable. Even with 2 quads mounted above bed, lots of firewood, and trailer attached (right at the max load of the tires). And these are only D rated...

But if I didn't need the flotation of the 16's, and I didn't mind paying the higher prices for wheels and tires, I would probably go with 18's to have a bigger "stability safety margin".