What happens to my milegae when I lift and install big tires?

[Overland Commander]

Plenty of people notice several impacts when they install bigger tires and a lift.

1. Speedo is off (you're going faster than indicated)
2. Mileage drops (takes more to run those big tires and get it moving)

Did you order gears and a device to re-calibrate the speedo?

Dont overstate the mileage impact - if you dont recalibrate the speedo/odo, you are using long miles to calculate the mileage and it is understated. I would guess over half the people that lift trucks never correct the speedo and think the mileage is what the truck tells them.

The fact is, if you go from 32" tires to 33" - you have changed the circumference by about 5%. So your speedo will be off by 5%. BUt your gas mileage will be more like 10% down iif you use the onboard milage because you didn't correct it. If not, it is double counting your tire increase by not using a correct mile.

 

[old_man]

It isn't so much that it takes more gas to move the big tires, but that the tires will lower the engine rpm's for a given speed. This can move you out of the power band for the engine and cause a loss of power and mpg's. A small tire diameter change is not a big deal but going from stock to 35's would necessitate a change in gearing to compensate.

 

[Overland Commander]

It isn't so much that it takes more gas to move the big tires, but that the tires will lower the engine rpm's for a given speed. This can move you out of the power band for the engine and cause a loss of power and mpg's. A small tire diameter change is not a big deal but going from stock to 35's would necessitate a change in gearing to compensate.

Plus rolling resistance. There's a bunch of factors in this. Even a 1" change is noticeable, but not a huge impact. To go from, say, 29 to 35 is huge, plus requires lift, lowering running gear, longer shaft, recalibration, regearing...

 

[The other Sean]

You can't really blanket statement this topic. Yes, your MPG and power will be down, but to what degree? Depends on how powered / underpowered your rig was to start. Tires? did you chose an all terrain that doesn't weigh a lot or a heavy Mud terrain? Do you daily drive your truck? is it mostly Highway miles?

When I lifted my truck and went from 32's to 33's, I chose Goodyear Duratracs as they were the lightest weight. I saw about a 1.5mpg loss. But... I'm 90% highway driving. I see more loss on tanks where I had more city driving.

when I added a full set of aluminum skid plates, my highway mileage went up a little. not quite 1mpg, but it was noticeable.

When I added large front mud flaps, I saw a 2 mpg loss...

 

[Desert Runner]

You can't really blanket statement this topic. Yes, your MPG and power will be down, but to what degree? Depends on how powered / underpowered your rig was to start. Tires? did you chose an all terrain that doesn't weigh a lot or a heavy Mud terrain? Do you daily drive your truck? is it mostly Highway miles?

When I lifted my truck and went from 32's to 33's, I chose Goodyear Duratracs as they were the lightest weight. I saw about a 1.5mpg loss. But... I'm 90% highway driving. I see more loss on tanks where I had more city driving.

when I added a full set of aluminum skid plates, my highway mileage went up a little. not quite 1mpg, but it was noticeable.

When I added large front mud flaps, I saw a 2 mpg loss...

This....it's all about DRAG

With tires it's rolling resistance.
With undercarriage...it's airflow.

Having a diesel engine will mitigate to a point the above observations. This is due to the torque they have which counteracts the drag applied.

On another note....it's nice to know that SKID plate additions can help with MPG, and not just protection [emoji2]

 

[Overland Commander]

This....it's all about DRAG

With tires it's rolling resistance.
With undercarriage...it's airflow.

Having a diesel engine will mitigate to a point the above observations. This is due to the torque they have which counteracts the drag applied.

On another note....it's nice to know that SKID plate additions can help with MPG, and not just protection [emoji2]

Now *that* is good info - I had not considered skid plates

 

[The other Sean]

I'm sure the caveat with the skid plates is the fact that I run aluminum ones and they cover nearly the entire underside of my truck and nothing hangs down under the truck.....

Each skid only weighs about 10lbs. If I was running steel, who knows. Though... once up to speed, vehicle weight doesn't matter as much.

 

[Desert Runner]

I'm sure the caveat with the skid plates is the fact that I run aluminum ones and they cover nearly the entire underside of my truck and nothing hangs down under the truck.....

Each skid only weighs about 10lbs. If I was running steel, who knows. Though... once up to speed, vehicle weight doesn't matter as much.

Aluminum or steel, I would just like better protection under my truck. Sticks...limbs...small rocks, the aluminum would work. Now steel would be best for that long gap between the cross members on each end of my Allison transmission.

Some companies offer aluminum with the caveat of being more show than go. VERY SAD. Obviously they use a too thin a gauge metal.....style over function. CRY[emoji2]

 

[Lindenwood]

I got 23 on my commute with my wife's 2016 4Runner when it had 33" MTs on 20x10 wheels. Going down to lightweight 32" ATs on 17x8, saving 50lb per corner, I got 24mpg on the same commute. Granted, I am pretty good at "hypermiling" my vehicles a bit, but the proportions shouldnt change too much.

Honestly it was not so big a difference that I would let me really sway me if I wanted one type of tire or another.

On the hypermiling thing, the main issue is bigger, heavier wheels and tires act like flywheels. They take more energy to accelerate, regardless, but you can recapture most of that energy by letting off the gas a little earlier and letting your vehicle's momentum, including the extra energy stored in the "flywheels," keep moving you along toward the stoplight.

 

[Overland Commander]

I got 23 on my commute with my wife's 2016 4Runner when it had 33" MTs on 20x10 wheels. Going down to lightweight 32" ATs on 17x8, saving 50lb per corner, I got 24mpg on the same commute. Granted, I am pretty good at "hypermiling" my vehicles a bit, but the proportions shouldnt change too much.

Honestly it was not so big a difference that I would let me really sway me if I wanted one type of tire or another.

On the hypermiling thing, the main issue is bigger, heavier wheels and tires act like flywheels. They take more energy to accelerate, regardless, but you can recapture most of that energy by letting off the gas a little earlier and letting your vehicle's momentum, including the extra energy stored in the "flywheels," keep moving you along toward the stoplight.

Thats about my experience too. I was getting 20/14 typically on the lighter 32". After the upgrade to 33" Coopers its 16/12.

In early testing, the mileage/HP chip I just installed today looks like a 20% gain back in MPG. Yesterday's running around town: 10.7 MPG. Today's, similar driving: 12.8. When I got into some steady state streets, I got up to 13.8. Dont know about highway yet, but the chip appears to work like advertised. Noticeable power gains, too.

For them as whats interested, its a Chip Your Car OBD plug-in, Stage 3. They advertise up to 50-60 HP and 5-8 MPG gains. So far, they're right.

www.chipyourcar.com

 

[Overland Commander]

I'm sure the caveat with the skid plates is the fact that I run aluminum ones and they cover nearly the entire underside of my truck and nothing hangs down under the truck.....

Each skid only weighs about 10lbs. If I was running steel, who knows. Though... once up to speed, vehicle weight doesn't matter as much.

Did you build these or get them from an outfitter? I'd be interested....

 

[The other Sean]

Did you build these or get them from an outfitter? I'd be interested....

Those come from Hefty Fabworks.