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Interesting JP tire comparison

Jeff Allan

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Nov 6, 2015
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When I was searching for info on tires over the last few weeks, http://www.fourwheeler.com/how-to/wheels-tires/154-1110-power-and-performance-from-weight-loss/ was one of the articles I found. Thought I'd share it as I found it really interesting to what we like and talk about. It's pretty much common sense that more weight at the wheels means a reduction in power and mpg... But I thought it'd be much more than what it really was. Very surprising at 28 #'s more per tire(!), mpg only dropped .63 mpg less. Now the HP and 0 to 60 times is more in line with what I'd guess.

For while I was scrutinizing over a few lbs. because I was reading all these guys saying for every lb. of unsprung weight, it's x10 in the jeep. they had all these calculations and stuff...it made my head spin more than my wheels.

There's also other factors which may it incredibly difficult to really know, like rolling resistance. What I read about the Duratrac is it has such good grip/traction and softer sides, that it can have more rolling resistance. Then there's tread depth which they say factors in. So many variables, you don't know until you know.
 
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Chris

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Sep 28, 2015
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Salem, Oregon
Yep, in a lot of ways this is one of those things where you don't know until you know.

Adding or reducing weight from rotating mass makes a HUGE difference though. MPG aside the best thing you can do when increasing tire size is to re-gear your rig. I went to 4.88 gears with 33" tires and my auto tranny and it's a night and day difference. Worth every penny!
 
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billiebob

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Oct 31, 2015
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Kootenays, BC, Canada
Gas mileage? Rolling resistance? Watch Tour de France. Ride a Mountain Bike... Then ride a Road Bike. Tires are the most important, easiest to change factor affecting gas mileage, rolling resistance. But to make a real difference the change needs to be dramatic. Which we TJ drivers tend to do to in the extreme to reduce our fuel economy.
 

Alex M.

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Oct 30, 2015
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Yeah, us TJ drivers are doing the opposite thing that most people are doing with their tires =]
 
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J

Jeff Allan

TJ Enthusiast
Joined
Nov 6, 2015
Messages
142
Gas mileage? Rolling resistance? Watch Tour de France. Ride a Mountain Bike... Then ride a Road Bike. Tires are the most important, easiest to change factor affecting gas mileage, rolling resistance. But to make a real difference the change needs to be dramatic. Which we TJ drivers tend to do to in the extreme to reduce our fuel economy.

28#/tire is what I'd consider dramatic change. yet the fuel savings is so miniscule. Even the HP didn't really suffer that much. Now the author of that article is surprised at those numbers and how much change resulted..... I guess he didn't read all the forums first. ha.
 
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billiebob

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Oct 31, 2015
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Kootenays, BC, Canada
From the article.. "A pound of rotating mass is like 10 pounds on the Jeep” for us Jeep-speakers". So 28# is 280# or 1000# total weight saving in Jeep speak. I know Driving alone or with 3 big guys as passengers makes no difference to my highway gas mileage... at least not a measurable one. And if the 2 tires are the same dimensions with the same tread? Good luck measuring any gas mileage difference.

For tires to make a difference they need to be real skinny and have no tread and run at higher pressures. Look to a Bonneyville Salt Flats racer for low rolling resistance which might make a measurable improvement.

Salt-Flats-Racing-Coupe-771.jpg
 
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mrblaine

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Nov 20, 2015
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Quail Valley, CA
From the article.. "A pound of rotating mass is like 10 pounds on the Jeep” for us Jeep-speakers". So 28# is 280# or 1000# total weight saving in Jeep speak. I know Driving alone or with 3 big guys as passengers makes no difference to my highway gas mileage... at least not a measurable one. And if the 2 tires are the same dimensions with the same tread? Good luck measuring any gas mileage difference.

For tires to make a difference they need to be real skinny and have no tread and run at higher pressures. Look to a Bonneyville Salt Flats racer for low rolling resistance which might make a measurable improvement.

View attachment 599
I think the biggest issue with not understanding the difference weight makes to our rigs is very few of us actually wheel where it makes a difference. If you aren't at the limit of performance, then anything you've done to hamper that performance won't be readily noticeable. As for the 3 large passengers, any effect they may have will be overcome and made less noticeable by your highway speed. If you get above around 60 mph, the wind resistance will make any other issue seem a pitiful detractor in comparison.
 
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Jeff Allan

TJ Enthusiast
Joined
Nov 6, 2015
Messages
142
When I haul gear, I can feel it harder to accelerate, and braking distance longer. Maybe not as noticeable on highway, but around town, I can feel when there's a lot more weight in the jeep. 1000 lbs. would be helluva lot, in a jeep. I don't know about the 1 lb=10 in the jeep. I read several times it's 4 lbs.in the vehicle for every 1 lb on the wheels, or below suspension. It's for every 10 lb.s, lose 1 HP. ha, who knows...
 

Sasquatchewan

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Joined
Dec 9, 2015
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211
Location
Laporte Texas
I could tell the difference in the width of a tire probably due to weight alone, but I still run a 33" KM2 but 11.5 instead of 12.5 made a good difference, also better steering response.
 

Bermudacat

TJ Enthusiast
Joined
Dec 28, 2015
Messages
249
From the article.. "A pound of rotating mass is like 10 pounds on the Jeep” for us Jeep-speakers". So 28# is 280# or 1000# total weight saving in Jeep speak. I know Driving alone or with 3 big guys as passengers makes no difference to my highway gas mileage... at least not a measurable one. And if the 2 tires are the same dimensions with the same tread? Good luck measuring any gas mileage difference.

For tires to make a difference they need to be real skinny and have no tread and run at higher pressures. Look to a Bonneyville Salt Flats racer for low rolling resistance which might make a measurable improvement.

View attachment 599
Great looking car. Form Follows Function and that looks like a ton of Fun!