Lift Kits and Bigger Tires for Trucks

What a lift kit actually does

A lift kit raises a truck or SUV's ride height above stock, most often to clear a larger tire than the factory fenders and suspension travel were designed around, and sometimes simply for extra ground clearance off-road. It changes how much room there is between the tire and the body or fenders, both at rest and through the suspension's travel.

Raising ride height on its own does not make a truck capable of running a bigger tire by itself; tire size is limited by how much room exists around the tire through its full range of motion, not just the gap visible with the truck sitting still. A lift is usually paired with a specific tire size in mind from the start, which is why most lift kits are sold, and shopped for, alongside a target tire size rather than as a standalone height change.

A lift changes more than clearance. It shifts the truck's center of gravity higher, changes suspension geometry and alignment angles, and, with a big enough tire added on top of it, changes the effective gearing the drivetrain is working through. All of that is covered later in this guide, and all of it is part of why a lift is a bigger decision than picking a height off a chart.

Leveling kits, spacer lifts and suspension lifts

A leveling kit is the smallest and most common type, correcting the mild factory rake many trucks have (sitting a little lower in the front than the rear, from the factory, with a load-carrying rear suspension) so the truck sits level front to rear. It usually raises only the front, by a modest amount, and is popular mainly because it lets a truck clear a modestly larger tire without a bigger, more expensive change.

A spacer lift adds a spacer above or below the factory spring or strut, raising ride height without replacing the spring itself. It is a simpler, generally less expensive way to gain a few inches of height than a full suspension lift, but it does not add extra suspension travel the way a true lift kit's longer components can, since it works with the factory shocks and control arms rather than replacing them.

A suspension lift replaces springs, shocks, and often control arms, control arm mounts, and other suspension geometry, to gain more height and, done well, more usable suspension travel along with it, not just static ground clearance. It is the most capable option for serious off-road use and the largest tire sizes, and it is also the most expensive and most involved to install correctly.

Tire size and what bigger actually means

A tire's size code, like 285/75R17, gives its section width in millimeters, its aspect ratio (sidewall height as a percentage of that width), and the wheel diameter it mounts to. See Wheel Offset, Width and Fitment and Tire Compounds, Treadwear and UTQG Ratings for more on reading that code and choosing a tire beyond its size.

Truck and off-road tires are also commonly described by their overall diameter directly, like a 33 inch or 35 inch tire, since that number is what actually decides how much room the tire needs around it, more directly than the size code alone does for most buyers shopping by fit. The arithmetic connecting the size code to that overall diameter is covered later in this guide.

Going up in tire diameter is the main reason most lift kits exist in the first place: a bigger tire needs more room, both at rest and through suspension travel and steering lock, than the stock tire the truck's fenders and suspension were designed around, and a lift is what creates that room.

Do you actually need a lift?

Some truck and SUV platforms can fit a modestly larger tire on factory suspension, sometimes with minor trimming, before a lift is needed at all, especially with a wheel offset chosen to help clearance. Checking what the specific platform supports on stock suspension is worth doing before assuming a lift is the first step toward a bigger tire.

A lift bought purely for looks, without a tire size goal or an off-road use case behind it, is a legitimate reason some owners choose one, but it is worth going in with clear eyes about the handling, ride, braking and legal trade-offs covered throughout this guide, since those trade-offs apply whether the lift's purpose is looks, capability, or both.

For a truck used mainly for towing or hauling on pavement, a lift and bigger, heavier tires generally work against that use case rather than for it, adding weight and raising the center of gravity without adding the capability the truck is actually being used for.

Warning signs after a lift and tire change

A lift and tire change touches enough of the truck's systems at once that a proper post-install check is worth taking seriously, not just a quick test drive around the block. The signs below are worth investigating before putting real miles on a newly lifted truck.

• A vibration that builds with speed, which can point at a driveshaft or CV angle issue introduced by the lift
• A speedometer that reads noticeably differently than it used to at a speed you can independently verify, a sign the electronic correction, if any, was not set for the new tire size
• Rubbing or contact anywhere in the wheel well at full steering lock or full suspension compression, not just at rest
• Noticeably longer or less confident braking than before, worth taking seriously given the added rotating and unsprung mass a bigger tire brings
• Uneven or rapid tire wear appearing within the first few thousand miles, which usually points at an alignment that was not rechecked after the lift

Choosing a lift type and height for the tire size you want

The starting point for choosing a lift is almost always the target tire size, not the lift height number by itself, since the lift exists to create room for that tire. A given tire size generally needs a minimum lift height to clear on a specific platform, and going with less lift than that minimum for the tire chosen is the most common way a lift and tire combination ends up rubbing.

Beyond the minimum needed for clearance, the choice between a leveling kit, a spacer lift, and a full suspension lift comes down to how much added suspension travel and off-road capability actually matters for how the truck is used, since a spacer lift and a suspension lift can land at a similar static height while behaving very differently once the suspension is actually working over rough terrain.

It is worth checking a specific lift and tire combination against what other owners of the same platform have actually run without rubbing, since published clearance specs can be optimistic and manufacturing tolerance on both the lift kit and the fenders themselves varies between individual trucks.

What a lift needs alongside it

A meaningful lift usually needs more than just the suspension components in the box. Longer brake lines, or an extension kit for the factory lines, are commonly needed once the suspension can travel further from the body than stock, since a stretched brake line at full droop is a real failure risk, not a cosmetic detail.

Driveshaft and CV joint operating angles change with a lift, covered in more depth in the advanced section of this guide, and a large enough lift often needs a driveshaft spacer, a longer driveshaft, or an adjustable track bar or panhard rod to keep those angles and the axle's lateral position within a reasonable range.

A bigger tire changes the effective final drive ratio the engine is working through, covered next, which is often addressed with new ring-and-pinion gears, sometimes called regearing, to restore the engine's operating range and the truck's towing and acceleration performance closer to what it had on the stock tire size.

Tire diameter arithmetic and speedometer error

A tire's overall diameter comes from its size code directly: diameter in inches equals the wheel diameter plus twice the sidewall height, where sidewall height is the section width in millimeters multiplied by the aspect ratio (as a decimal), converted from millimeters to inches by dividing by 25.4.

A speedometer and odometer are calibrated to the stock tire's revolutions per mile. A bigger tire covers more ground per revolution, so for a given actual road speed the wheel turns slower than the stock tire would, which means the speedometer, still reading off the same revolutions-per-mile assumption, under-reports actual speed once the tire is meaningfully larger than stock. The odometer under-reports distance traveled the same way.

The size of that error tracks closely with the percentage change in overall diameter: a tire about 7% larger in diameter than stock produces a speedometer reading roughly 7% slow, so a speedometer showing 60 mph is closer to an actual 64 mph on the road. Many trucks let this be corrected electronically once the new tire size is entered into the instrument cluster or a tuning device; on trucks without that option, the error has to be accounted for by the driver instead.

Regearing: restoring the truck's effective gearing

A bigger tire effectively taller-gears the truck, the same way a taller final drive ratio would, since the engine now turns fewer revolutions to cover the same distance. That shows up as duller acceleration, more work for the engine to maintain speed (especially towing or climbing a grade), and, on an automatic, a transmission that may not kick down and hold gears the way it used to for the same conditions.

Regearing corrects this by changing the axle's ring-and-pinion ratio to compensate for the tire's larger diameter. The common approach is to scale the stock gear ratio by the same ratio the tire diameter changed by: new gear ratio is approximately the stock ratio multiplied by the new tire diameter divided by the stock tire diameter, which restores the engine's revolutions per mile close to what it was on the stock tire.

Regearing is a real mechanical job, not a bolt-on part, and it is usually done at the same time as a significant tire upsize specifically because the truck is already apart for other lift-related work. See gearing for how effective gearing is treated elsewhere on the build sheet.

Common mistakes

The most common mistake is buying a lift height based on a general chart rather than confirming it against the specific tire size and wheel offset actually being run, since two owners of the same platform running different offsets or slightly different tire sizes can need different lift heights to clear without rubbing.

A second common mistake is skipping regearing on a large tire upsize, especially on a truck used for towing, then being surprised by sluggish acceleration, poor fuel or energy efficiency, and an automatic transmission that hunts for gears or runs hotter than before under load.

A third is not rechecking the alignment and driveline angles after the lift settles in, treating the install as finished once the truck is back on the ground, when ride height, alignment and driveline angle can all shift slightly as new components settle over the first several hundred miles.

Effective gearing and torque at the wheels

A bigger tire changes more than the speedometer, it changes the torque actually delivered to the road for a given amount of engine torque, since torque at the wheel scales inversely with the tire's rolling radius: the same engine and axle torque produces less effective force at the contact patch through a larger-radius tire, the same basic leverage relationship as a longer wrench needing less force for the same turning effort, run in reverse.

This is on top of the effective gearing change covered earlier: a larger tire acts like a taller overall gear ratio, reducing engine rpm at a given road speed, and reducing wheel torque for a given amount of engine torque at the same time, both pulling acceleration and towing performance in the same direction unless regearing corrects for it.

Regearing restores the engine's operating rpm range and, largely, the wheel torque relationship the truck had on its stock tire size, but it does not change the tire's actual rolling radius or the physics of leverage described above; it changes the axle ratio to compensate for that changed radius, which is a different thing from eliminating the effect.

Load, center of gravity and braking

A taller truck raises its center of gravity, and a heavier, larger-diameter tire adds both weight and, per the physics covered in Weight Reduction: What It Gains and Costs, rotating and unsprung mass, all of which work against braking distance, cornering stability, and rollover resistance rather than for them.

One standardized way this is measured for a whole vehicle is static stability factor, a metric NHTSA uses in its vehicle rollover resistance rating, calculated as track width divided by twice the height of the center of gravity: a wider, lower vehicle has a higher (safer) static stability factor, and a taller vehicle with the same track width has a lower one.

Braking distance is governed by how much kinetic energy the brakes have to absorb, which scales with the vehicle's mass, and by how much force the tires can actually transmit to the road, which depends on the tire's grip and the load on it; a heavier tire and wheel package, on top of any added vehicle weight from the lift itself, increases the energy the brakes have to absorb for the same starting speed, without necessarily increasing the tire's grip in proportion.

Driveline and CV joint operating angles

Raising ride height changes the operating angle of the driveshaft and its universal joints, or the CV joints on an independent front suspension, relative to the transmission, transfer case or differential they connect to. Universal joints and CV joints are each designed to operate smoothly within a range of angles, and larger operating angles generally increase vibration and wear, with the specific tolerance depending on the joint's design and how fast it is spinning.

On a solid axle truck with a driveshaft and U-joints, a large lift often needs a driveshaft angle correction, commonly a wedge or shim at the axle's pinion, a slip-yoke spacer, or a longer or adjustable driveshaft, to bring the operating angle back into a comfortable range rather than leaving the joint working at an angle well outside where it was designed to run smoothly.

On a truck with an independent front suspension, a lift changes CV joint operating angle at the front axle shafts directly, and very large lifts on this type of front end can push those angles further than the factory shafts are comfortable with, which is part of why very large lifts on independent front suspension trucks sometimes call for a diff drop kit or similar geometry correction, not just longer suspension components.

State height and bumper laws

Many places regulate how high a vehicle's bumper or frame can sit above the ground, separate from any rule about tire size itself, and the details of that rule (what is measured, from what reference point, and what the limit actually is) vary by state and can change over time. See lift height for how a lift's legality is treated on the build sheet, and state rules for how state-specific requirements are handled generally.

The practical effect is that a lift height legal in one state can be over the limit in another, and a truck registered in one state but regularly driven or later re-registered in another needs its own state's current rule checked, not the rule of wherever the lift was originally installed. See registration state and use for why the state a vehicle is registered and driven in is what actually governs which rules apply.

Because these rules change and differ enough to make a specific number unreliable to print here, the right step before a large lift is checking the current rule directly with the state's vehicle inspection or motor vehicle authority, not relying on a shop's general experience with other states or an outdated forum post.

What experienced builders check

An alignment check after any lift is treated as mandatory, not optional, since every angle covered in Wheel Alignment: Camber, Caster and Toe changes with ride height, and a lift moves ride height by definition.

Driveshaft operating angle is checked with an angle finder at both ends of the shaft, not assumed acceptable just because the truck drives smoothly at low speed in the driveway, since vibration from an angle slightly outside its comfortable range often only shows up at highway speed or under load.

Corner weights and tire pressure are rechecked once the lift and new tires are installed, since the combination changes both the truck's balance and how much load each tire is actually carrying, which affects the tire's rated capacity and the vehicle's actual stopping and handling performance versus what the stock spec sheet assumed.