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Discussion Starter · #1 ·
What are the main factors that effect MPG and power when changing tires?
Weight? Diameter? Width?

In general, will a similar spec'd AT tire get better on-road MPG performance than it's MT counterpart just because of tread pattern and rubber compound?
 

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Bigger tire, more weight, less MPG and more power to generate rotations in the short.


Yes.
 

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What are the main factors that effect MPG and power when changing tires?
Weight? Diameter? Width?

In general, will a similar spec'd AT tire get better on-road MPG performance than it's MT counterpart just because of tread pattern and rubber compound?
All of the above...

Of course heavier tires have a higher rotational inertia and take more effort to get them rolling (horsepower/torque) and stopped (brakes). Higher rolling resistance could be caused by grippier tread patterns, softer rubber compounds, softer (less rigid) tire construction, or even a wider contact patch. And when you think about it all these factors combined describe pretty much every aftermarket tire I've seen on any FJ here. Just the nature of the beast I guess. :cheers:
 

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Discussion Starter · #4 ·
Indeed. I figured as much but I was just making sure. So just out curiosity, do FJ's that come from the factory with the offroad package (TRD wheels and BFG AT KO's) have worse gas mileage than the ones that come with the alloys and Duellers? Looking up the specs for BFG's, their weight is significantly more than the Duellers and comparable to my current Kumho MT's. I don't remember ever reading that anyone got significantly less MPG's with the BFG's. Does the compound of my MT tires make that much of a difference when paired against the BFG's that are of similar weight?
 

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im curious to this as well.. i understand more rubber more weight or anything over then stock application will yield less mpg.. since i have the 08tt with the 16 trd wheels how big of a difference is it from the 17's? being that both tires the BF and duns have the same overall diameter (height) with the 17's having less sidewall rubber are there any big differences in weight between the trd and stock aluminum? i've heard that the TT's that come with the 16's with BF tires yield less mpg is this true?
 

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Tread design/pattern also plays a huge roll.

A super swamper TSL has a much higher rolling resistance than a stock hwy tire.
 

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Weight of the rim comes into play as well.

Tire pressure will play a factor.
 

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Has anyone with stock fj's that have replaced their 17 stock wheels/tires with the trds and standard bf a/t's notice any difference in mpg? i'm thinking about trying this if it yield better mpg with the 17's and standard tires.. if it does i wouldnt mind having a street set and a trail set
 

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Has anyone with stock fj's that have replaced their 17 stock wheels/tires with the trds and standard bf a/t's notice any difference in mpg? i'm thinking about trying this if it yield better mpg with the 17's and standard tires.. if it does i wouldnt mind having a street set and a trail set
The difference would be small btw the two. But, the AT's would have slightly worse economy. They are a heavier tire and more aggressive tread.

Why would you run a trail set of tire and use all terrains? Why not sell those tires and run a bigger more aggressive tire if just using for the trails.

My "street tires" are 285 BFG ATs :lol:
 

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Discussion Starter · #10 ·
im curious to this as well.. i understand more rubber more weight or anything over then stock application will yield less mpg.. since i have the 08tt with the 16 trd wheels how big of a difference is it from the 17's? being that both tires the BF and duns have the same overall diameter (height) with the 17's having less sidewall rubber are there any big differences in weight between the trd and stock aluminum? i've heard that the TT's that come with the 16's with BF tires yield less mpg is this true?
Well they may have the same diameter, but since you're shrinking your wheel diameter, you'll have more rubber that adds to the weight. Which is what happened to me. I took off my 17" steelies/Duellers and put on 16" alloys/MT's and lost 1.5MPG almost on the dot. Sometimes it's 2MPG. I'm just wondering if I swap out the MT's for AT's with less aggressive tread but at the same weight if I'll even notice a difference.
 

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Do they make like a passenger car tire that would fit the FJ so you could get better MPG for commuting, then put on your offroad tires if you were going to a rally or whatever? My vehicle is dual use, so I'm trying to come up with creative ways to get the most bang for my buck.
 

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Well they may have the same diameter, but since you're shrinking your wheel diameter, you'll have more rubber that adds to the weight. Which is what happened to me. I took off my 17" steelies/Duellers and put on 16" alloys/MT's and lost 1.5MPG almost on the dot. Sometimes it's 2MPG. I'm just wondering if I swap out the MT's for AT's with less aggressive tread but at the same weight if I'll even notice a difference.
Rolling resistance is a fairly big factor, but I believe weight was of more consequence that RR when I researched this a few months back. Obviously there is a reason why Fed Ex and UPS run such tall, lean, tires on their vehicles, as well as the post office trucks: lowest rolling resistance and stiffest compounds possible, and thinnest tire patch= greatest miles per gallon.

I had switched from the Duncraps to Goodyear AT/S tires 3 years back, and noticed no change in mileage at all, not one bit. I assume it was due to the fact that the tire weight was the same as Duncraps, but the compound was tougher. So despite the tread pattern being much more aggressive in relation to the Dunlops, I lost no mileage. This is stock size, and on 17 alloy.

I am betting that you won't see much change at all, at least negligible.

I know several people that took a mild mpg hit when they went to BFG KOs or the Good Year Silent Armor tires, and the Dura Tracks but in the stock tires size. Again, mainly due to the increased unsprung weight of the heavier tire material, and the more aggressive tread.

Didn't have time to check this...(sorry), but I believe the general rule is for every 10lbs of added unsprung weight, it is like adding an additional 100lbs of static weight to the vehicle. So if you went from a 41lb Dueller to a 53lb Silent Armor or BFG...it would be like adding nearly 400lbs of additional static weight to the vehicle. That would kill your mpg in a big way. Add to that then the added rolling resistance, and you're no longer 19/23....you're 12/19

Hope this makes sense. Someone check the unsprung weight / static weight facts for me please.

Cheers
 

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Do they make like a passenger car tire that would fit the FJ so you could get better MPG for commuting, then put on your offroad tires if you were going to a rally or whatever? My vehicle is dual use, so I'm trying to come up with creative ways to get the most bang for my buck.
There are, but I only recall seeing a couple with the designated Passenger rating on them. Most at LT, AT types like the Dunlops or Duellers.

The only way to get better mileage from a tire, factually, is if you went with a lighter, small/thinner tire with at least the same rolling resistance as the stock tires. That's why cars in the mid-late 70's had pizza cutter tires....virtually little to no rolling resistance: very little power to push very little weight on very low resisting rolling mass tires through dense air. :)
 
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