Posted by Jason Locke on 5/2/2020 to Before you Buy
It's pretty much a rite of passage for an F150 owner to throw a leveling kit or lift on their truck and then chuck on a set of big tires. However, this is not without a few issues. Larger tires mean that your truck's final drive ratio gets thrown off, which also throws off your shifting and acceleration due to changes in final drive ratio, and heavy tires means your truck's powertrain is going to struggle more to turn those tires in the first place. The solution is either regearing or tuning (or both...we'll get to that), but which you should choose is always a debate among the F150 faithful. There's good arguments for both, but there's a lot that the various forums and online truck gurus tend to not take into account a few quirks and issues that you may run into when you're trying to narrow your own choice down between shorter gears and tune to compensate for larger and heavier tires. In general, we here at Stage 3 lean towards the tuning route for most folks, however, there are a few trucks and a few situations where regearing is good option.
What Happens When you Add Big Tires onto your F150While adding bigger tires onto a truck is pretty-much one of those "must-do" upgrades for your average F150 and give you and your truck big benefits when it comes to ground clearance, traction, and looks, there are two major problems when jumping up tire sizes. The first is that the larger diameter of the tires throws off your truck's final drive ratio which effects your speedo readings, odometer readings, transmission shift points, and skew RPM at speed lower. Skewed RPM is one of the more noticeable impacts of bigger tires on untuned trucks with factory gears, since the lower cruising RPM means that your truck could sit outside of its natural power band and get you luggy acceleration and force more downshifting when you punch the throttle. Throwing off your shift points further causes issues, since you'll have to provide more throttle input in order to get the truck to shift. The second issue is that bigger tires are heavier. This seems like a common-sense point, but a lot of folks underestimate just how much a bigger tire can weigh, especially if you're going from an SL to an E-rated LT. For instance, the LT305/65R18 Falken Wildpeak A/T3Ws that I have on my truck weigh 66lbs per tire versus your average P-rated 265/60R18 weighs in the neighborhood of 30-35lbs. All that weight has to be turned by something, and you'll need either more power or more mechanical advantage to make up the difference.
Tuning or Regearing on the EcoBoost F150sInstead of looking at tuning or regearing individually, we're going to look at the different F150 motor options to see if tuning or regearing is the better option. First up, the 3.5L EcoBoost and 2.7L EcoBoost trucks. For the 2011-2020 EcoBoost trucks, we generally recommend tuning over regearing. The EcoBoost trucks tend not to have issues with larger tires, in general (at least up to a certain point). While the shift in RPM can change power band, the EcoBoost trucks tend not to have much of a band at all. The EcoBoosts have a ton of low-end torque and tend to keeping making good levels of torque until they get heat-soaked in the upper RPM reaches. There's not a lot to get skewed in the first place. Secondly, since the EcoBoost trucks make a bunch of power off a tune alone, doing gears is just not cost-effective. You can grab a tuning device for under $500 that will add more than enough power to compensate for the tires and even add a smidge back to fuel economy in a device that anyone can use. Doing front and rear ring and pinion gears (assuming a 4WD truck) is far more expensive. Components alone are usually over $1000, and then install can be another $1000 on top of that. It's just not worth it when tuning will do the job.
Tuning or Regearing on the 5.0L, 6.2L, and 3.7L F150sThe argument between regearing and tuning gets a little more interesting on Ford's naturally-aspirated F150 motors, especially the 5.0Ls. Despite being similar to the 5.0L Coyote in the Mustangs, the 5.0L in the F150s has some pretty key differences that reduce its compression ratio to get peak torque lower in the power band. Ford was only partially successful, and the 5.0L Coyote in the F150s make peak torque in the middle of the RPM range (4250rpm, according to the literature). That mid-range peak torque poses a problem when it comes to the way RPM skews lower with larger tires. The shift in RPM means that the 5.0L won't really be in its ideal power band at cruising, and these trucks tend to lug and downshift a lot with big tires (especially on the 6-speed trucks). Now, tuning can help, since tuning can at least change shift points and add enough power that trucks with slightly bigger tires likely will get back to near-stock acceleration and performance. However, even the best tune doesn't alter that general power band, and if you have big enough and heavy enough tires, a tune may not quite get the job done. Regearing, on the other hand, actually fixes the power band issue by changing that final drive ratio and getting RPMs back on track. You still end up paying a lot more doing a gear swap than tuning, but if you're running fairly large tires, jumping up to new gears is likely the way to go. The 6.2L and 3.7L trucks have the same story, though the 6.2L tends to hold onto power a little more effectively than the 3.7L and 5.0Ls. Regearing can also potentially help improve your truck's overall fuel economy, since the transmission will downshift less to give you the acceleration you need. Now, you'll still likely lose some fuel economy at highway speeds, since you'll be running at a higher RPM, but around town or in areas where speed tends to vary more, you can see a bump in fuel economy as long as you're not getting too aggressive with your gearing (i.e. 4.56s, 4.88s, or 5.13s). We currently have Nitro's 4.11 Complete Gear Package and an Eaton TrueTrac installed on our 2011 F150 5.0L XL (owned by yours truly), and the gears have made a huge difference with how this truck drives.
Why Not Both Tuning and Regearing?Good question, skippy. Ideally, you'll be able to add both shorter gears and tuning to your truck. The gears will win you back the mechanical advantage your truck needs, while your tuning device of choice will get you some extra power and correct your speedo and odometer readings for both the tires and the gears. Granted, what's "ideal" and "what my wallet can support" are two very different things. If it comes down to one or the other, then you do have a choice to make based on your truck's motors, what size tires you're running, fuel economy considerations, and what kind of performance you want out of your truck. Like most things, the choice between tuning or regearing your F150 doesn't really have a wrong answer. Everything depends on what you're trying to do with your truck. If you do need any more assistance with making your tune or gear decision, give us a call directly at 623-434-5277.
F150 EcoBoost Tuning Options:
- 2018-2020 F150 3.5L EcoBoost Tuners & Monitors
- 2018-2020 F150 2.7L EcoBoost Tuners & Monitors
- 2015-2017 F150 3.5L EcoBoost Tuners & Monitors
- 2015-2017 F150 2.7L EcoBoost Tuners & Monitors
- 2011-2014 F150 3.5L EcoBoost Tuners & Monitors
- 2018-2020 F150 5.0L Tuners & Monitors
- 2015-2017 F150 5.0L Tuners & Monitors
- 2011-2014 F150 5.0L Tuners & Monitors