So How Much does Extra Weight Effect Things

[Muskoka Minute]

I have a 2019 2 Door Rubicon and am going to go from 33" to 35" Tires.
Here is there weight difference between BFG KO2s and Micky Thompson Baja Boss A/T. (see chart)
Just wondering from your expertise how much does the extra weight effect things like -
- Steering feel
- Stopping distance/feel and brake life
- on road, off road characteristics
- I know fuel mpg goes down

Sorry for the size..

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[tomk62]

Think about this for a moment, the heaviest difference is around 75 pounds which I'll go out on a limb and say this is roughly half the weight of an average adult, or the weight of a pre-teen child. My Labrador retriever is 100 pounds. So it would be like driving around all the time with less then another person in the vehicle with you.

Am I crazy, or are we over thinking the weight issue?

 

[Chupacabra]

Think about this for a moment, the heaviest difference is around 75 pounds which I'll go out on a limb and say this is roughly half the weight of an average adult, or the weight of a pre-teen child. My Labrador retriever is 100 pounds. So it would be like driving around all the time with less then another person in the vehicle with you.

Am I crazy, or are we over thinking the weight issue?

I agonized over this too. I don't think it's the relatively minor extra weight, it's *where* the weight is - at the wheels. It has an oversized effect on handling, braking, acceleration, etc. Can also have an impact on spare tire carrier too once you start getting up over about 85 pounds.

 

[Heimkehr]

By way of example, my winter wheel/tire combo weighs 20 lbs. more at each corner than does the OEM wheels/tires. Note that this is unsprung weight.

From experience, I know that, in isolation, winter-blend gasoline reduces my average fuel mileage by ~2 MPG. Driving around with the winter wheels/tires installed reduces it by another 2.x MPG (that particular metric was purposely measured/determined before winter gas was at the pumps.)

The combined fuel mileage penalty rounds up to -5 MPG.

I observed no material difference in steering feel. Braking effort on cold, dry surfaces was mildly increased, but hardly enough to worry about or debate.

 

[Paluss]

Think about this for a moment, the heaviest difference is around 75 pounds which I'll go out on a limb and say this is roughly half the weight of an average adult, or the weight of a pre-teen child. My Labrador retriever is 100 pounds. So it would be like driving around all the time with less then another person in the vehicle with you.

Am I crazy, or are we over thinking the weight issue?

Thats true, but a passenger is Sprung weight that the vehicle is designed to handle by the suspension.

Unsprung weight (tires, wheels, brakes, etc) has more of an impact because it involves rotation/momentum of each wheel, so the more Unsprung weight, the worse MPG, 0-60, handling, braking, and more wear on the components attached to each wheel...

 

[Zissou]

Think about this for a moment, the heaviest difference is around 75 pounds which I'll go out on a limb and say this is roughly half the weight of an average adult, or the weight of a pre-teen child. My Labrador retriever is 100 pounds. So it would be like driving around all the time with less then another person in the vehicle with you.

Am I crazy, or are we over thinking the weight issue?

You're missing a pretty important detail about where the weight is. Specifically this is unsprung weight, which matters a whole lot more than sprung weight.
Literature on unsprung weight: https://eeuroparts.com/blog/unsprung-weight/

The rotational mass of the wheels and tires matters a ton more than what's in the car. Even my girlfriend who is not a gear head noticed the difference when we swapped her Sport S stock wheels/tires for the 33's that were on my Gladiator.

Specifically you will feel the weight in acceleration more than anything.
You may also feel the difference in turn-in due to the tires being taller and essentially more squishy bits between you and the road, especially if you are going from a highway tire to an all-terrain tire.
Braking I have not noticed any difference, but also didn't test any extremes luckily.

Now, if you are off-roading you will take this trade off for the larger tire. That said if you can get a lighter wheel and/or tire in the same size then it will be better on the road. How much better comes down to your sensitivity. I am fairly sensitive, but I'm also a sports car enthusiast (in addition to Jeeper).

When I hunted down 35's for my Gladiator I specifically picked one of the lighter weight options (which were the BFG All Terrain KO's). They weighed roughly the same as the Falken Wildpeak 33's, which helped that poor V6 lug around the heft of the Gladiator with larger tires.

 

[Muskoka Minute]

By way of example, my winter wheel/tire combo weighs 20 lbs. more at each corner than does the OEM wheels/tires. Note that this is unsprung weight.

From experience, I know that, in isolation, winter-blend gasoline reduces my average fuel mileage by ~2 MPG. Driving around with the winter wheels/tires installed reduces it by another 2.x MPG (that particular metric was purposely measured/determined before winter gas was at the pumps.)

The combined fuel mileage penalty rounds up to -5 MPG.

I observed no material difference in steering feel. Braking effort on cold, dry surfaces was mildly increased, but hardly enough to worry about or debate.

Interesting
I run a designated snow tire in the winter which is the same as my factory weight, so this is a non issue.
I'm leaning towards the Micky Thompson A/t which weights in approx. 18.6lb per corner. (or 98lb for the set of 4) Which is more or less the same as your winter combo.
Did you find any excessive wear on other components? I know its a tough one to quantify.

 

[Muskoka Minute]

Generally one or two people and yes all of the above...

 

[TheRaven]

Tire weight is HUGE. Get the lightest tires you can.

I can give a couple of examples.

1 - On my previous truck (2010 Tahoe) I went from the factory 32's to 33" Duratracs (275/70R18). At the time, the only load range that existed in that size was E. So I ended up adding more than 20lbs to each corner. That cost me 2-2.5mpg, and the ride was stiff and harsh. Three years later Goodyear launched a D-range version of the same tire so I replaced my E's with the D's. The D's were 8lbs lighter per tire (measured on my calibrated hanging scale). I got 1-1.5mpg back just from that change. Same size, same tread, just less weight. I also got a much more forgiving ride quality from those tires.

2 - On my current truck (2021 Silverado) I went from the factory 32's to 35" Goodyear Territory MTs. The Territory MTs are amazingly light tires (the 315/70r17 came out to a hair over 50lbs on my hanging scale), and as a result, I lost no perceptible fuel mileage. Then I put on a steel high-clearance bumper and lost over 1mpg, but that's a different story.

3 - Two weeks ago I put the same 35" Territory MTs on the Wrangler (going from 33" Ridge Grapplers) and also lost no MPGs. Furthermore, since i'm stuck with sport gearing, the light tires help to mitigate the downsides to much larger tires...still got plenty of passing power and i'm still seeing the upper gears on the highway. Note - when I went from the factory 32's to the C-range Nitto 33's (7lb increase per tire if I remember correctly), I lost just under 1mpg.

You really want to go as light as you possibly can on the Wrangler. You can't tow enough to warranty the heavier range tires, and unless you are crawling on razor blades, C-range tires are tough enough.

Oh and also make sure you calibrate your JL for the change - otherwise you'll have no idea the results of the change and lots of things won't work right.

 

[Heimkehr]

Did you find any excessive wear on other components? I know its a tough one to quantify.

Not that I can affirmatively authenticate.

What I mean by that is that, late last year, I had to have one of the front wheel hubs replaced due to a failed bearing. I had both front hubs replaced for the sake of symmetry and safety.

While it's possible that the increased weight of the winter wheel/tire combo caused accelerated wear to the OEM component, if that did occur, it only occurred on one of the four hub assemblies. More to the point, our mild winter thus far means that I didn't yet have the snow shoes installed. So, the failed part was filed in the "It Happens" folder and that was that.

 

[Vinman]

Back in the day it was generally accepted that unsprung rotational weight had a 4 to 1 disadvantage over sprung weight.
IE: 100 lbs of additional unsprung weight was equivalent to 400 lbs of sprung weight

 

[Muskoka Minute]

Thanks for all the great info guys.
Its great being able to draw on all the wealth of first hand knowledge that is out there.

Cheers!

 

[Valpo Jeep]

Rotational mass is the big thing with tires. I found a formula to use.

1 lb of rotating weight = 8.4 lbs of static weight.

adding 75 lbs with the tires would be like adding 630 lbs of static weight

https://www.signaturewheel.com/sing... wheels,car's performance, every ounce counts.

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