Stock tires to BF KO2s - mpg?

[Waffle34]

so im sure youve seen those retro silverados around online. I got a set of the steel wheels already sandblasted and powder coated. They of course are 17" steel rims. I have the usual aluminum 18" rims with 265/65R18 goodyear  tires on my truck now. I am planning to get BF KO2's for the 17" steel rims in 265/70R17 which is virtually the same diameter and circumference. One less revolution per mile so meh.

I do drive alot of highway miles and curious how much of a MPG hit the KO2's will cause. I can pretty easily get 22-24 mpg highway now. 

 

Anyone got any real world figures? Even just staying factory size on the same rims not necessarily doing my exact swap.

[CamGTP]

If the rolling weight is the same or very similar, probably not much change at all.

 

Just don't buy load range E tires as those are much heavier.

[MikeBMW]

35 minutes ago, CamGTP said:

If the rolling weight is the same or very similar, probably not much change at all.

 

Just don't buy load range E tires as those are much heavier.

I Bought the load range E K02 35X12.5X18s for hauling and towing. New stock black aluminum wheels.
If I was worried about gas mileage, I wouldn't have changed a thing about the stock form and tires.
I just wanted a lift and a better looking truck, IMO.
Still, if one is worried about gas mileage, keep it stock.
I never understand why people wanting to mod their truck are concerned about gas mileage.
It'll be what it will be, I guess.
Currently, I'm at 10 MPG around town, I have yet to take it on a highway drive for any extended length of time but I'll be doing that next month - from Florida to Colorado - to help my Mom out after my Dad passed away. (flew out for the funeral and drove the BMW to the airport because the truck ain't gonna fit in the parking garage - Tampa is 6'8" for short term)
I'll update later.

Edited June 15, 2021 by MikeBMW

[Waffle34]

56 minutes ago, CamGTP said:

If the rolling weight is the same or very similar, probably not much change at all.

 

Just don't buy load range E tires as those are much heavier.

yea i tried finding the factory tires on tirerack but no dice. the BFko2's in load range C are about 46 lbs a tire. Closest i can find on tirerack are about 36-38 lbs for the factory goodyear wranglers.

 

looked at general grabber at/x and they are still 45 lbs each.

 

i did run the steel wheels with the factory load range E tires for a few months and it didnt affect mpg that much (but we were on winter gas too) - those are about the same 45 lbs each now that i think about it. kinda slipped more in the snow.

 

While im not super concerned about mpg it would be nice to know. Ive added the tow mirrors and did a 2" front level kit. neither of those affected mpg too much. I do plan to get an 18 ft open car hauler in the near future to tow a project truck around - trailer and project combined will be close to 6000#.

1-2 mpg drop wont be the end of the world but if its 5-10 like some people are saying elsewhere thats going to be a big deal....

 

Edited June 15, 2021 by Waffle34

[2015 High Miler]

I think its a reasonable question to see what the difference is in a real world comparison.

 

I currently have 32" Michelins that are rated at 43# each. I would like to go up to a 33 or 34" tire.  The weight difference on most tires I've looked at is about 15# each.  I do a lot of long highway runs and losing 1-2 vs 3-5 is a lot of difference. Adding 60# of rotating weight is significant. But, how significant?  1-2 I can live with but 4+ is not worth it to me. 

 

I added BFG AT on our Jeep and lost 2-3.  It went from 21-22 to 18-19. Same height but wider and much heavier that the stock passenger car tire that came on it.  Also, added wheels so there is extra weight there, too.  

 

Point is, asking about MPG loss with a tire change seems like a reasonable request.  

 

 

 

 

[asilverblazer]

Using stock size, I haven’t noticed any significant changes in mpg. I am using heavier lad range. 

[Grumpy Bear]

Picture a ping-pong ball on a foot and a half length of 100# test fishing line and your spinning it over your head at say 10 rpm.

 

Now replace the ping-pong ball with a 10# Medicine Ball and imagine that same 10 rpm orbit.

 

Try is with a 50# boat anchor. 

 

Now do it with four weights at a time and that is the basic concept of wheel weight. Even up to speed it will take more effort to keep the heavier weights aloft and at that same 10 RPM. 

 

Basic flywheel math. Speed, mass and distance are all contributors and the higher that total 'flywheel' effect the more fuel it will use. 

[2015 High Miler]

Bear thanks for the reply but it doesnt answer the question of how much difference.

 

Current tires are Michelin Defender LTX 305/50/20 that list at 42#.

Im looking at BFG 33/12.5/20 that list at 56#.  

 

How much difference is expected?  

 

Does anyone have any figures?

[Grumpy Bear]

1 hour ago, 2015 High Miler said:

Bear thanks for the reply but it doesnt answer the question of how much difference.

 

Current tires are Michelin Defender LTX 305/50/20 that list at 42#.

Im looking at BFG 33/12.5/20 that list at 56#.  

 

How much difference is expected?  

 

Does anyone have any figures?

Not me.