If you're building an off-road truck or SUV, there's a good chance you'll eventually face one of the most common questions in the 4x4 world:

Should I run 35s or step up to 37s?

At first glance, the difference doesn't seem very significant.

After all, we're only talking about two inches of advertised tire diameter.

But those two inches can affect much more than appearance.

Moving from 35-inch to 37-inch tires can change:

• Ground clearance

• Tire weight

• Effective gearing

• Acceleration

• Braking

• Fuel economy

• Steering feel

• Suspension clearance

• Fender clearance

• Wheel offset requirements

• Drivetrain load

• Spare-tire fitment

• Off-road capability

And here's the part that surprises many people:

A 37 doesn't give you two additional inches of ground clearance compared with a 35.

It gives you roughly one inch—and often less in the real world.

So is that extra inch worth everything else that comes with 37s?

Sometimes absolutely.

Sometimes not.

Let's look at the real differences between 35s and 37s so you can decide which tire size makes sense for how you actually use your vehicle.

First: A "35" Isn't Necessarily 35 Inches Tall

Before comparing anything, there's an important detail to understand.

The number printed on the sidewall doesn't necessarily represent the tire's actual installed diameter.

A tire labeled:

35x12.50R17

may measure somewhere around the mid-34-inch range depending on the manufacturer and tread design.

Likewise, a:

37x12.50R17

may measure somewhere in the 36-inch range.

Actual dimensions vary based on:

• Manufacturer

• Tire model

• Tread depth

• Wheel width

• Inflation pressure

• Vehicle load

Once the tire is mounted on the vehicle, its effective rolling radius is also reduced slightly by the weight of the vehicle.

So when comparing tires, don't rely solely on the size molded into the sidewall.

Check the manufacturer's specifications for:

Overall diameter, section width, tread width, weight, and revolutions per mile.

Those numbers tell you much more.

How Much Bigger Is a 37 Than a 35?

Nominally:

37 - 35 = 2 inches

But tire diameter grows in both directions from the axle centerline.

That means the axle only moves upward by half the increase.

So going from a true 35-inch tire to a true 37-inch tire theoretically increases axle clearance by:

1 inch.

That's the important number.

You're not gaining two inches beneath the differential.

You're gaining approximately one inch.

And because many advertised 35s and 37s don't actually measure their nominal sizes, the real difference can sometimes be slightly less.

Where Larger Tires Actually Increase Ground Clearance

This is one of the strongest arguments for larger tires.

A suspension lift raises:

• Frame

• Body

• Rock sliders

• Bumpers

• Some suspension components

But on a solid-axle vehicle, a suspension lift generally doesn't raise the differential housing farther from the ground.

A larger tire does.

Likewise, on independent suspension vehicles, tire diameter increases the distance between the wheel centerline and the ground.

This means larger tires can improve clearance at areas that a suspension lift alone cannot.

That extra inch between 35s and 37s may not sound dramatic, but in technical terrain it can be the difference between:

Clearing a rock

and

Dragging a differential, skid plate, or suspension component across it.

Approach, Breakover, and Departure Angles

Larger tires can also improve off-road geometry.

Because the entire vehicle sits slightly higher relative to the ground, 37s can improve:

• Approach angle

• Breakover angle

• Departure angle

The difference usually isn't enormous when moving from 35s to 37s, but every little bit helps on technical trails.

A larger tire can also contact an obstacle sooner and begin climbing it rather than allowing the bumper or bodywork to reach it first.

37s Roll Over Obstacles More Easily

Ground clearance isn't the only advantage.

Larger-diameter tires generally roll over obstacles more easily.

Imagine trying to roll:

A skateboard wheel over a curb

versus:

A bicycle tire over the same curb.

The larger wheel encounters the obstacle at a more favorable angle.

The same basic principle applies off-road.

A 37-inch tire can roll over:

• Rocks

• Ledges

• Ruts

• Roots

• Washouts

slightly more easily than a 35.

Again, the difference isn't transformational—but in difficult terrain, incremental improvements matter.

35s vs. 37s: The Weight Difference

Here's where things start working against the larger tire.

A 37 is usually heavier than a comparable 35.

Depending on construction and tire model, the difference might be several pounds per tire—or considerably more.

Suppose your 35 weighs:

65 pounds

and the comparable 37 weighs:

75 pounds.

That's:

10 additional pounds per tire

or:

40 pounds across four tires.

Include the spare and you've added:

50 pounds.

And this isn't ordinary cargo weight.

Most of it is both:

Unsprung weight

and

Rotating mass.

Those are important distinctions.

Why Rotating Weight Matters

Adding 40 pounds of tires isn't equivalent to putting a 40-pound bag in the cargo area.

Your drivetrain has to accelerate the tires rotationally.

Your brakes have to slow them rotationally.

And the suspension has to control their movement vertically.

Larger tires therefore affect:

• Acceleration

• Braking

• Suspension response

• Steering feel

• Fuel economy

And because much of a tire's mass is located relatively far from the center of rotation, that weight has a meaningful effect on rotational inertia.

This is why tire weight should be one of the specifications you check before buying, not an afterthought.

Not All 37s Are Equally Heavy

This is worth emphasizing.

Tire construction matters tremendously.

A heavy-duty mud-terrain designed for extreme rock use may weigh substantially more than a lighter all-terrain or rugged-terrain tire of nominally the same size.

That means:

A lighter 37 may have less impact on drivability than an extremely heavy 35.

Size alone doesn't tell the entire story.

Always compare actual tire specifications.

How 37s Affect Gearing

As we explained in our guide to regearing, larger tires effectively make your axle gearing taller.

Let's say your vehicle currently has:

35-inch tires and 4.70 gears.

Moving to 37s changes the effective ratio to approximately:

4.70 × 35 ÷ 37 = 4.45

So your 4.70-geared vehicle now behaves approximately like it has 4.45 gears relative to the previous tire diameter.

That's about a 5.4% gearing change.

That may not sound huge, but combine it with additional tire weight and rolling resistance and the difference can become noticeable.

Do You Need to Regear Going From 35s to 37s?

Not automatically.

A powerful modern vehicle with:

• Strong low-end torque

• An 8- or 10-speed transmission

• Appropriate factory axle gearing

may handle the transition perfectly well.

Other vehicles may become noticeably sluggish.

You might experience:

• More frequent downshifts

• Reduced acceleration

• More throttle required

• Reduced engine braking

• Worse towing performance

• Less low-speed control off-road

If you're already unhappy with the vehicle's performance on 35s, installing 37s probably won't improve matters.

That's when regearing deserves serious consideration.

Acceleration: 35s Have the Advantage

All else being equal, 35s will generally accelerate more easily than 37s.

Why?

Two reasons:

1. Smaller diameter provides more effective mechanical leverage.

2. The tire is usually lighter.

This doesn't mean a truck on 37s is necessarily slow.

Modern turbocharged engines and multi-speed transmissions can mask the difference extremely well.

But physics still applies.

If acceleration and throttle response are priorities, the 35 has an inherent advantage.

Braking: Another Advantage for 35s

The same rotational mass you had to accelerate now has to be stopped.

Larger, heavier tires increase the demands placed on the braking system.

The larger tire radius also increases mechanical leverage against the brakes.

That doesn't mean factory brakes suddenly become unsafe when you install 37s.

Many vehicles handle them perfectly well.

But compared with an equivalent 35-inch setup, 37s generally require the braking system to work harder.

This becomes increasingly important when the vehicle is also carrying:

• Steel bumpers

• Winch

• Skid plates

• Rock sliders

• Roof rack

• Camping equipment

• Recovery gear

A heavily modified vehicle can become substantially heavier than stock.

Fuel Economy

If maximizing fuel economy is high on your priority list, neither 35s nor 37s are likely to help.

But 37s generally carry a greater penalty.

Why?

Potential contributors include:

• Greater rotational mass

• Increased rolling resistance

• Wider tread

• More aggressive tread patterns

• Taller vehicle ride height

• Increased aerodynamic drag

• Altered effective gearing

The exact MPG difference varies tremendously.

Some vehicles may show only a small change.

Others may lose several MPG.

Driving style and vehicle configuration matter greatly.

37s Can Affect Transmission Behavior

Modern automatic transmissions are remarkably adaptable.

But larger tires change the load placed on the drivetrain.

With 37s, you may notice the transmission:

• Holding lower gears longer

• Downshifting more frequently

• Using the highest overdrive gears less often

• Hunting between gears on hills

• Responding differently while towing

Proper tire-size calibration can help the vehicle's computers understand the new tire diameter.

But remember:

Programming doesn't restore mechanical leverage.

Only gearing can do that.

35s Usually Require Fewer Vehicle Modifications

This is one of the biggest practical advantages of 35s.

Depending on the vehicle, 35s may require relatively modest changes.

Possibilities include:

• Small suspension lift

• Leveling kit

• Appropriate wheel offset

• Minor liner modification

• Removal or modification of crash bars

• Alignment

37s can be considerably more demanding.

Depending on the vehicle, fitting 37s may involve:

• Additional lift

• Different wheel offset

• Aftermarket upper control arms

• Fender liner modifications

• Crash-bar changes

• Bumper trimming

• Body-mount modifications

• Steering upgrades

• Regearing

• Spare-tire carrier upgrades

Not every vehicle requires all of these.

Some modern off-road vehicles are surprisingly 37-friendly.

Others require substantial work.

Wheel Offset Becomes More Important With 37s

Larger tires occupy more physical space.

As tire diameter and width increase, wheel positioning becomes increasingly important.

Move the wheel too far inward and the tire may contact:

• Upper control arm

• Shock or coilover

• Sway bar

• Suspension components

Move it too far outward and it may contact:

• Fender

• Fender liner

• Bumper

• Body mount

• Crash bars

This is why simply adding more negative offset isn't always the solution.

Moving the tire outward may solve an inner-clearance problem while creating an outer-clearance problem.

And as we've discussed in our scrub-radius guide, moving the tire farther outward also changes steering geometry.

A 37 Can Rub Where a 35 Doesn't

This seems obvious, but the reason matters.

A larger tire doesn't simply occupy more space while driving straight.

It follows a larger arc when steering.

Now add suspension compression.

The tire needs enough clearance while:

Turning + compressing + articulating.

That's much harder than clearing the tire while the vehicle sits stationary in the driveway.

This is why:

"It fits."

and

"It doesn't rub."

aren't necessarily the same thing.

A proper off-road fitment should account for the suspension's usable travel and steering range.

Lift Height Isn't the Whole Answer

One of the biggest misconceptions in tire fitment is:

"I have a 3-inch lift, so 37s will fit."

Maybe.

Maybe not.

Lift height is only one factor.

You also need to consider:

• Wheel offset

• Wheel width

• Tire width

• Actual tire diameter

• Caster

• Suspension design

• Bump-stop position

• Fender shape

• Body mounts

• Bumper clearance

In fact, excessive outward wheel positioning can sometimes cause a large tire to rub more severely during steering even though the vehicle has plenty of lift.

35s vs. 37s for Daily Driving

For a vehicle that spends most of its time commuting, 35s often represent an excellent compromise.

They provide:

• Aggressive appearance

• Significant ground clearance

• Strong off-road capability

• Lower weight than comparable 37s

• Easier fitment

• Better acceleration

• Better braking

• Less drivetrain stress

• Lower replacement cost

For many owners, 35s provide virtually everything they realistically need.

That doesn't make 37s wrong.

It simply means you should have a reason for stepping up.

35s vs. 37s for Rock Crawling

Technical rock crawling is where 37s begin making a stronger argument.

The larger tire provides:

• More ground clearance

• Better obstacle rollover

• Larger footprint when aired down

• Potentially improved traction

• Improved approach/breakover/departure geometry

An extra inch under the axle can be genuinely useful when rocks are constantly threatening differentials and suspension components.

For difficult trails, those incremental advantages add up.

35s vs. 37s in Mud

In mud, tire diameter can help because a larger tire may:

• Increase ground clearance

• Reach through deeper material

• Maintain momentum

• Provide a larger footprint

But tread design, tire width, vehicle weight, and wheel speed can matter as much as diameter.

A 37-inch all-terrain isn't automatically a better mud tire than an aggressive 35-inch mud-terrain.

Choose the tire for the terrain—not just the number on the sidewall.

35s vs. 37s in Sand

Sand is heavily influenced by flotation.

Larger tires can provide a larger footprint when properly aired down.

But:

Air pressure is enormously important.

A properly aired-down 35 may dramatically outperform a 37 running excessive pressure.

Vehicle weight, tire construction, and tread pattern also matter.

Again, diameter is only one part of the equation.

35s vs. 37s in Snow

Bigger isn't automatically better in snow.

Snow conditions vary.

In deep, soft snow, a larger footprint may improve flotation.

In shallow snow over a firm surface, a narrower tire may cut through the snow and reach traction underneath more effectively.

Tread design, compound, siping, tire pressure, and width can matter more than the difference between 35 and 37 inches.

Tire Pressure and Airing Down

One of the biggest advantages of off-road tires is the ability to reduce pressure on the trail.

Airing down allows the tire to:

• Conform to terrain

• Increase contact area

• Improve traction

• Absorb impacts

• Improve ride quality

A 37 has more sidewall and air volume than a comparable 35 when wheel diameter is the same.

That can be beneficial off-road.

For example, a:

37x12.50R17

provides more sidewall than a:

35x12.50R17

on the same 17-inch wheel.

That additional sidewall can improve compliance and obstacle conformity.

17-Inch Wheels Make a Lot of Sense With 35s and 37s

For serious off-road use, many enthusiasts prefer 17-inch wheels with these tire sizes.

Why?

More sidewall.

Compare:

37-inch tire on a 17-inch wheel

with:

37-inch tire on a 20-inch wheel.

The 17-inch wheel provides substantially more tire sidewall.

That generally improves:

• Air-down capability

• Ride compliance

• Wheel protection

• Tire conformity over obstacles

Large wheels may look appealing, but for functional off-road builds, more tire and less wheel often provides real advantages.

What About Spare Tires?

Don't forget the fifth tire.

A 37-inch spare is larger and heavier than a 35.

That can create issues with:

• Factory spare mounts

• Tailgates

• Tire carriers

• Rear visibility

• Bumper clearance

On some vehicles, a reinforced or bumper-mounted tire carrier may be advisable.

And yes—you generally want a spare that's reasonably close in rolling diameter to the tires on the vehicle.

Running a significantly smaller spare can create drivetrain concerns, particularly depending on the differential and four-wheel-drive system.

Storage Can Become an Issue Too

A 37 is physically big.

If your spare is stored:

• Under the vehicle

• Inside the cargo area

• On a rear door

• On a swing-out carrier

verify that it actually fits.

Sometimes the forgotten spare creates more trouble than the four tires on the ground.

37s Cost More

This seems obvious, but don't only compare purchase price.

Consider:

• Initial tire cost

• Shipping

• Mounting

• Balancing

• Replacement cost

• Spare tire

• Possible gearing

• Suspension modifications

• Tire carrier

• Steering components

• Calibration

The difference between a 35-inch build and a 37-inch build may be far greater than the price difference between the tires themselves.

37s Can Accelerate Wear

Large tires don't automatically destroy components.

But bigger and heavier tires can increase loads on:

• Wheel bearings

• Ball joints

• Tie rods

• Steering racks

• Axles

• CV joints

• Suspension bushings

Add aggressive wheel offset and those loads can increase further.

A properly designed vehicle may tolerate 37s very well.

But compared with 35s, you're generally asking more from the mechanical components.

Don't Forget Your Garage

Here's a practical issue people sometimes discover too late.

A suspension lift plus larger tires increases overall vehicle height.

If you park in:

• Residential garage

• Parking garage

• Carport

• Low-clearance structure

measure first.

Roof racks, rooftop tents, and antennas can make the problem even worse.

The best 37-inch build in the world isn't much fun if your truck no longer fits in the garage.

So Who Should Choose 35s?

35s make a lot of sense for someone who wants:

• Strong off-road capability

• Aggressive appearance

• Reasonable daily drivability

• Easier fitment

• Lower tire weight

• Better acceleration

• Better braking

• Less drivetrain impact

• Lower overall build cost

For a vehicle that's driven to work during the week and explored on weekends, 35s are often the sweet spot.

They're large enough to provide meaningful off-road benefits without necessarily turning the rest of the vehicle into a major project.

Who Should Choose 37s?

37s make more sense when:

• Technical off-roading is a priority

• Ground clearance is genuinely important

• You regularly encounter large obstacles

• You're willing to modify supporting systems

• The vehicle has adequate power and gearing

• You're prepared for additional weight and cost

• You simply want the stance and appearance of 37s and understand the trade-offs

There's nothing wrong with choosing 37s because you like how they look.

Appearance is part of why we modify vehicles.

Just understand what comes with them.

When 37s Make Sense Even If You Don't "Need" Them

Let's be realistic.

Very few enthusiasts need 37-inch tires for driving to work.

And most modified 4x4s aren't crossing the Rubicon every weekend.

Sometimes the answer is simply:

You want 37s.

That's perfectly valid.

The important thing is making an informed decision rather than assuming they're simply 35s that happen to be two inches taller.

They're part of a larger system.

Build around them properly and they can work extremely well.

A Quick 35s vs. 37s Comparison

Category	35-Inch Tires	37-Inch Tires
Ground Clearance	Very Good	Better
Obstacle Rollover	Very Good	Better
Weight	Lower	Higher
Acceleration	Better	More Impact
Braking	Easier	More Demand
Fuel Economy	Better	Typically Worse
Fitment	Easier	More Difficult
Regearing Need	Less Likely	More Likely
Steering Load	Lower	Higher
Component Wear	Lower	Potentially Higher
Daily Driving	Excellent Compromise	More Trade-Offs
Technical Off-Roading	Very Capable	Advantage
Cost	Lower	Higher
Appearance	Aggressive	Very Aggressive

Don't Choose Tire Size Based on Appearance Alone

Before deciding between 35s and 37s, ask yourself:

What kind of terrain do I actually drive?

If your trails rarely challenge the clearance provided by 35s, 37s may not provide much functional benefit.

How much highway driving do I do?

Daily drivers benefit more from keeping weight and gearing reasonable.

Am I willing to regear?

Maybe you won't need to—but you should consider the possibility.

Am I willing to modify the vehicle for proper clearance?

A tire that technically fits but rubs every time the suspension compresses isn't a successful fitment.

How much additional weight am I adding?

Compare actual tire specifications.

Can my steering and suspension handle the additional load?

Particularly if you're also changing wheel offset.

What is my total budget?

Consider the entire build, not just the four tires.

The Better Question Isn't "Can I Fit 37s?"

This may be the most important takeaway from the entire article.

People frequently ask:

"Can I fit 37s?"

That's not really the right question.

With enough cutting, lifting, spacing, and modification, you can fit enormous tires on almost anything.

The better question is:

"What do I have to change to make 37s work properly, and are the benefits worth those changes for how I use my vehicle?"

That's the question that leads to a good build.

The Bottom Line

The jump from 35s to 37s looks small on paper.

It's only two inches of nominal tire diameter.

But those two inches affect much more than ride height.

A 37 generally provides:

More ground clearance.

Better obstacle rollover.

More sidewall and potential footprint.

A more aggressive appearance.

But it also usually brings:

More weight.

Taller effective gearing.

Greater braking demand.

More difficult fitment.

More steering and suspension load.

Higher cost.

Greater potential need for supporting modifications.

For many daily-driven off-road vehicles, 35s represent an excellent balance between capability and practicality.

For vehicles regularly tackling more difficult terrain—or owners willing to accept the additional compromises—37s can provide meaningful benefits.

Neither size is universally better.

The right tire is the one that matches your:

Vehicle + drivetrain + suspension + terrain + budget + expectations.

And before choosing either one, look beyond the number printed on the sidewall.

Compare the tire's actual diameter, weight, width, construction, load rating, and intended terrain.

Because when you're building an off-road vehicle, the best tire isn't necessarily the biggest tire you can make fit.

It's the tire that makes the entire vehicle work better for the way you actually use it.