33" tires (50-55lb) or 34" tires (60-67lb)?

I've been looking at the tire weights of the OEM Offroad and Trailhunter tires and they're 36 and 40lb respectively. The Trailhunter tires are these I believe: https://www.americastire.com/buy-tires/goodyear-wrangler-territory-rt/p/152084?storeCode=1734

I can barely believe how light the OEM tires are. The TH/Pro 33s appear designed for the EPA, with 11/32nds of tread depth. Great way to help the environment, by ensuring all these tires wind up in the landfill in 20k miles.

I'm seeing 50-55lb weights for LT load-range-C 33" (285/70R17) tires like BFG KO2. The 34" variety (285/75R17) are 60-65lb (and harder to find in load-range-C).

How much of a performance / mileage hit are you all seeing by upgrading to real tires on these trucks? I'm looking at getting a 2025 with a manual (i.e. non-hybrid, slowest, least economical).

The 34s look much better (they don't even look that big) but concerned it'll wreck the drivability/long-distance cruising performance/MPG. I'll definitely be sticking to load range C.

Stock wheel tire is 65lb/corner (TRD offroad)
Trailhunter is probably 72-75lb. (Guessing)
33s on 17s would be 79-84lb. (50-55lb tire)
34s on 17s would be 89-96lb. (60-67lb tire)

Truck will see plenty of offroad and deep snow (Wyoming).

Appreciate any advice. Truck is still a few months from arriving so have plenty of time to mull this crap.

 

Also I'm planning to lean toward the lighter end of the ranges.....probably KO2 if I went 33 (51lb) or Toyo AT3 if I went 34 (59lb).

 

just had a flat on my OE falkens 33's that came on my OR hybrid. at 8k miles they only have 7/32 tread left.. anyway im leaning towards toyo AT3 also when i buy new. in stock 33" size

 

Great Thread and Timely.

My truck is currently on 285/70/17 GY Duratrac Load Range D and I am looking to go to a 34" (285/75/17) but like you posted, the weights are significantly more.

I am tuned in for the responses.

 

I’m running the BF Goodrich KO3 in 265/70/18 load E. Supposedly the C or D will be available late summer.

I lost a little over 1 mpg moving from the stock 265/70/17 Trail Terrain on my OR.

I like the ko3 just fine. Running 37 psi presently. Wet pavement grip seems ok but I haven’t really tested them much. I need to go to the high school stadium and do some hard brake testing in the rain.

 

I fit BFGoodrich 33' All Terrain T/A КО3 LT 285 /70 R17 and Method Race Wheels MR703 on my SR without a lift. I love em, have had no issues and they look great, I take it off roading on the farm and performs like a beast.

 

Why not these 35s at 55lbs?

 

Do it. Tell us how it goes.

 

If I ever go to a 4g I will. Too much work to fit on my 3g

 

I've been thinking allot about this topic, how much performance in acceleration/braking do you lose when changing tire size (mass). Although not perfect, I've tried approaching this by doing a simple Moment of Inertia calc for comparison between stock and larger Rim/Tire selections. I'm hoping to get a general understanding of how much extra power does it take to accelerate different size setups relative to stock. Looks like this in my spreadsheet so far:



If anyone is interested in my spreadsheet, it's attached, feel free to grab it and evolve it for your own application. I find it helpful in scenario modeling, when you can find accurate weight information on Rims/Tires.

I've noticed the more aggressive off-road tires are ungodly heavy compared to stock A/S tires. This soaks power and braking performance by the numbers and I've experienced this in real-world applications in the past. This "engineered" approach allows me to quantify it to a degree.

Cheers!

 

Ooh, I love this. So much thrown around here based on anecode and opinion, then we get real data from a critical thinker, who also acknowledges the method's imperfection. Thank you for elevating the discussion to rational.

I'm hoping you know the physics better than me and can add your thoughts on this question. I think that moment of inertia calculations assume that the mass is all out at the periphery of the distance upon which the force is applied. The wheels and tires however distribute that mass with a center of mass closer to the center of rotation. Is there any way to account for this in your calculations? If I'm right (unlikely perhaps) then I think your calculation would be overestimating the increase in rotational inertia with increased tire weight?

You'll soon get questions about effect on MPG, and I have a feeling that involves so many variables it would be impossible to come close to calculating. But if you can do it you'll get a TW Nobel.

 

This is a good topic that I have thought about as well. Excellent points and analysis here! I thought about larger tire size, but don't want to negatively impact overall performance. I will keep my stock tires for now and when they need replacing I will opt for a high quality all terrain, since the OEM versions are usually scaled down.

 

Heh, heh, thanks for the kind words Roalddahl!

So the point you raise of the position of the mass is at least one of the flaws in this study, however the flaw is consistent between the stock and modified scenarios, so it at least represents the relative change, you just have to take the resulting number with a grain of salt. This study, due to the simplistic nature of the equation I chose to use, takes the mass and averages it equally across the rotational radius. To do anything any more complex requires me to move more towards a three-dimensional model. Similarly, my simple model does not take into account factors such as frictional losses within the drivetrain when changing loads, differences in coefficient of friction in the two different tires which potentially creates additional rolling drag, aerodynamic differences and so forth...all of which can play some minor role in the accuracy of the model.

I'm hoping this concept can inspire somebody to take it to another level of accuracy from where I left off.

 

It's a hard pill to swallow, but seemingly a universal truth with many things...and that is, to keep performance levels equal, it seems we have to look at the system as a whole. So if you go with larger tires and wheels, to keep stock levels of acceleration and braking performance you necessarily have to consider going with lighter wheels (which may also not be as strong), changing final drive ratios (front and rear for most of our trucks) and add more power. All of this most likely comes at the price of decreased mpg not to mention the hard investment cost of the system wide changes.

I first came across this way of thinking when I was a much younger man when I asked my uncle "What would be the best cam for me to put in my car?" His response was frustrating for me to hear, but wise in "Depends on what you want to do. Drive to work every day reliably, keep it stock. Race your buddies from stop light to stop light, that's a different cam. Race on weekends down a quarter mile, that's a different cam. Do high speed runs on the Salt Flats, that's a different cam as well. Also, what do you plan to do with the rest of the intake system, the rest of the exhaust system, heads, ignition, carburation (showing my age here), transmission gearing, differential gearing...? It all has to work together to be optimal."

The easier choice is to simply shift our values in priority and just say "I don't care about going and stopping performance, I want better slow, off-road performance." Or perhaps that is not it, maybe its just "I don't care about the numbers, I just want to look at my truck and say "damn that's cool looking" which is also great." In the end, I guess it's all about what we're wanting as an end result that helps us decide.

 

Correct me if I'm wrong but aren't stock tires not "real" tires but merely a cheaper version of the brand tires? Maybe thats why they are so light.

 

Yeah, lower tread depth and commonly a different tread pattern. I had Wildpeak AT3Ws (non-OEM, bought from Tirerack) on my 22 Taco and the tread is a proper A/T tire (but with more siping for better winter traction). The "AT3Ws" on friend's 24 Tundra TRD Pro look like Falken's "highway terrain" version of the tire and have half the tread depth. My Wildpeaks had the 3PMSF (three-peak-mountain-snowflake) rating for proper winter traction, his do not. I was thrilled with the winter performance of the "real" AT3Ws in snow/ice, but the Tundra ones seem to slip and step out of line at any opportunity, as though they're worn out.

 

Right… my week old taco OR also has the cheapo falken tires. I’ll be getting rid of it asap.

 

The BF Goodrich Trail Terrain 265/70/17 tires that came on my OR were 36 pounds. The BF Goodrich KO3 265/70/18 load E tires I have now are 57 pounds. That's a non trivial difference. I took at least a 1 mpg hit on gas mileage, but I don't mind.

 

33s all the way. SL load.

 

How did you find the center of mass (or rotational equivalent)? Wouldn’t the distribution of weight be vital to accurate calcs?