Big tire upgrades are all the rage and usually one of the first modifications 4WD truck owners have planned. How the bigger 35” tires will affect your gas mileage largely depends on the vehicle’s power output and a host of other variables. Remember, with big tire upgrades, it doesn’t only affect mpg but also affects braking, steering, handling and performance.
So, what is the average MPG difference when upgrading from a 33” MT to a 35” MT?
You can expect 1 to 2 mpg difference when upgrading from 33” to 35“tires. The larger diameter, width and circumference add to the unsprang weight which has a direct effect on fuel economy, performance, gearing and other drivetrain components.
What if you decide to make the switch from a 33” MT to a 35” AT? MT tires are generally heavier due to the multiple plies, aggressive tread patterns, and deeper lugs. Will moving to a 35” AT from a 33” MT have that much of an impact on gas mileage?
Let’s find out!
Gas Mileage Difference between 33 and 35” Tires
So we’ve established that you will see a decrease in MPG when switching to a bigger 35” MT tire. Users who have made the switch have reported a decrease of anything between 1-2mpg when cruising on the highway and 2-4mpg when driving in the city. Of course, the trucks low-down torque and overall performance outputs plays a major factor and figures will vary from vehicle to vehicle.
It’s not uncommon for Jeep Wrangler owners to fit 35” tires, since they have SFA and plenty of options to improve wheel clearance. Of course, re-gearing is key. Once you fit 35s it recommended to go with either the 5.13 or 4.88 gears. Even though frugal gas mileage shouldn’t really be your main concern when driving a 4WD, many JK owners report a drop of between
Let’s see what to expect when fitting 35” tires to your truck
Difference between 33″ and 35″ Tires Explained (Size/Height/Weight)
Yes, there are many important factors to consider when squeezing bigger tires on your truck.
Those factors include but not limited to:
- Can The Drivetrain handle the weight?
- What’s the Minimum Suspension lift required?
- Does your truck have enough torque to accommodate the added unsprang weight?
- Articulation/Down travel – will you be going off-road?
- CV Angles (IFS) – will I need a diff-drop kit?
- Bump-stops – How will it affect wheel travel and articulation off-road?
Yes, sure, a larger tire will in most cases increase ground clearance and overall off-road performance, provided your vehicle has enough torque to move those heavy tires and your drivetrain can accommodate the additional weight. Don’t forget the additional re-gearing of diffs.
What you really need to be asking is, are the added complications that are part and parcel with big 35” tire upgrades worth it. For example, most SFA trucks with 33s will be just as capable 99% of the time compared to those with 35s. Sure, there will always be a situation when the larger tire will outperform. The question then is, how often will this situation arise and will the added hassle and major cost of fitting 35’s justify the amount of times you’ll actually NEED it? This highly depends on the application.
I guess it all depends on the level of wheeling you enjoy doing, or if the truck is a dedicated off-road rig and not being used as a daily driver.
The 35” tire will offer approximately 1” of clearance on the axle, but let’s look at some other factors you need to consider first. These are just some of the factors that will be affected.
- Diff Strength
- CV Joints (IFS)
- Fender Clearance
- UCA Clearance
- Wheel offset /Backspacing
- Gear ratios
- Speedometer accuracy
- Fuel Consumption
- Torque at the wheels
Read more about the differences between 33” and 35” tires here. (Size/weight/performance)
What User Say
I would say maybe 1 mpg less. I had 285/70/17 (32.8) and went to 315/70/17 (34.4) and lost about 1 mpg. The look of the bigger tires is well worth it in my opinion. Still get around 14.5 to 15.https://www.f150forum.com/f4/33s-vs-35s-mpg-comparison-158993/
For 2 years i got 285 miles to a 26 gallon tank on 295/70R18 Terra Grapplers. I put my 275/70R18 Cooper LTZ’s back on my truck and now i’m back up to around 340 miles to a tank.https://www.f150forum.com/f4/33s-vs-35s-mpg-comparison-158993/index2/
With 35’s, I’d say you’re gonna drop 1-2 mpg around town assuming you also regear. If you don’t regear, you’re gonna drop probably 2-4. On the Hwy, I think you’ll drop probably similarly. With 33’s, not really sure but somewhere shy of the above numbers but probably not by too much. The key is to regear and get the power better delivered again to the tires and therefore you MPG will come back closer to normal (but not all the way back to factory/stock).https://www.jk-forum.com/forums/modified-jk-tech-2/33-vs-35-gas-mileage-17131/
35” tires and your Drivetrain
Because the weight sits below the sprung suspension it falls part of unsprang weight. This added weight has a direct effect on fuel economy, performance, gearing and other drivetrain components. But a 35″ tire is going to put more strain on the drivetrain to perform and to haul the 4WD over obstacles off-road. Yes, it gives you the extra 1″ of clearance, however, there are negative aspects to it as well.
Does 4WD Use More Gas?
4-wheel drive trucks use more gas since it has more drivetrain components and overall weight when compared to a 2WD of the exact same make and model. 4WD’s have more drivetrain components such as an extra differential, transfer case, and an extra driveshaft, to name a few.
These major components all add to the weight, friction and rotational mass which negatively affects fuel consumption. When you add additional unsprang weight in the form of big 35” MT tires, you exacerbate the gas usage problem, thus decreasing your MPG.
First determine what the primary application for the upgrade is. If improved aesthetics and a more aggressive stance your goal or will you need maximum practicality, off road ability, while maintaining maximum articulation. If you’re not taking it off-road anyway and the look doesn’t bother you, go low profile since a low rolling resistance helps somewhat.
In conclusion, the sheer weight, wind resistance, friction, and rolling resistance combined with rotational mass of 4WD drivetrain components will always result in lower gas mileage no matter how you swing it.