Rolling Resistance - Weight vs Size

I'm researching new tires and I'm curious about rolling resistance. I'm torn between getting 255s or 285s. I want a larger diameter tire, don't really care if I get a wider tire (no need to comment on this, there are hundreds of threads on it). I actually really like the width of my current tire. With my wider rim, the St Maxx will go to roughly 10.6 width (not tread but tire). Here are the details:


Current Setup:
- 265/75/r16 E-rated BFG KO2s
- 2" lift
- Method 701s, 0 offset 4.5 bs


Considering:
- 255/85/r16 Cooper ST Maxx
--- Diameter: 32.8
--- Width: 10.2
--- Weight: 59lbs
--- Load: E

- 285/75/r16 Duratrax (or other 285s)
--- Diameter: 33.1
--- Width: 11.3
--- Weight: 54lbs
--- Load: E


My question is - What affects rolling resistance more, weight or size of a tire? 5lbs per wheel is a decent amount of weight to add. But a wider tire has greater contact with the ground. I've researched this but having really found any meaningful answers. Thanks in advance for any insights. Cheers!

 

I went from a E load tire to the exact same tire in C load, 53 lbs to 45 lbs. I went from 16 mpg avg to 17 mpg avg. Not a huge difference.

 

The weight will affect how the truck feels to drive more than the tire size itself. Of two same-sized tires, the heavier will feel more sluggish. Of two same-weight tires, the larger will feel more sluggish. At some fixed radius they will have the same effect on inertia, but since you’re keeping the radius the same (both options are 33” tires) the weight is what will slow you down.

 

try this. I found this 30sec ago https://www.tacomaworld.com/tirecalc?tires=265-70r17-285-70r17

 

This might be of interest, although not a direct answer to your question:
https://www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison

It would be awesome if there was an equivalent website for truck tires. My understanding is that all being equal, the rubber compound and suppleness of the carcass will have the most effect on rolling reistance, not weight or width. SL tires will have a lower rolling resistance to that of a E load.

Rolling resistance only affects mileage at cruising speed, weight will have bigger effect on mileage during acceration, which is a inertia thing, not a friction thing (i.e., rolling resistance).

 

Here is a good read for you.

https://www.tacomaworld.com/threads...eel-tire-combo-trd-rock-warriors-ko2s.381030/

 

FYI, Cooper also makes the AT3-LT in a C-load 265/75R16.

 

Some people: ^

Me: hehe foot on rectangle make wheel go vroom

 

Right on. FYI, I am not the author of the post I quoted, I just thought it was a pretty comprehensive read on rolling resistance which is what the OP was asking about. But yes, there are various makes in C load sizes which are lighter than E load tires. Some of them are also pretty heavy which is something that can affect rolling resistance and MPGs. I think Michelin's have some specifically designed low rolling resistance tires and the compounds used in the tire do matter greatly which is something to keep in mind.