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What Are The Biggest Tires That Fit A Stock GMC Sierra 1500?

GMC Sierra 1500 owners swear by the power and utility that their full-size, half-ton American trucks offer. However, for aesthetic/performance-related reasons, many Sierra owners like to upsize their tires.

Luckily, we researched the biggest tires you can fit on a completely stocked GMC Sierra 1500, and here's what we found.

For the 4th-generation (2014-2018) GMC Sierra 1500, you can fit tires up to 32.5 inches in overall diameter. However, most 5th-generation (2019-present) Sierra trims can accommodate true 33-inch tires straight out of the dealership.

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On the other hand, the current-generation trail-ready Sierra trims (AT4 and AT4X) can fit up to 34.8-inch tires.

Are you thinking about upsizing the tires on your GMC half-tonner? Read on because we'll help you explore your options and give you the pros and cons of mounting larger tires on your vehicle. With that said, let's dive right in!

Used GMC Sierra 1500 AT4 pickup truck. With supply issues, GMC is buying and selling used and pre-owned vehicles to meet demand., What Are The Biggest Tires That Fit A Stock GMC Sierra 1500?

What Are The Biggest Tires You Can Put On A GMC Sierra?

Black GMC Sierra Denali truck showing the aftermarket black wheels

As the flag-bearer of the Sierra line, the half-ton Sierra 1500 accounts for over 50% of the nameplate's unit sales. The Sierra 1500 is popular both for recreational and practical purposes.

To improve the looks and performance of their trucks, many GMC Sierra owners opt to upsize their tires. For pickup trucks and SUVs, tire upsizing is one of the easiest and most affordable ways to achieve both aesthetic and practical customization goals.

So what is the biggest tire size you can fit on a stock GMC Sierra 1500? It depends on the year model of the truck.

GMC Sierra Tire Sizes

For the GMC Sierra 1500s released from 2014-2018, you can fit up to 32.5-inch tires without cutting, trimming, or suspension modification.

On the other hand, current-generation GMC Sierra 1500s already have bigger wheel well clearances.

Thus, from 2019 to the present, most Sierra 1500 trims already have a factory option for 33.1-inch tires. However, you can still go up to 33.5 inches on some non-off-road trims.

Here are some possible tire sizes you can choose for upsizing based on the rim size and model year of the Sierra 1500.

  • 17-inch rims
    • 255/80/R17 - 33.1 inches
    • 285/70/R17 - 32.7 inches
  • 18-inch rims
    • 285/65/R18 - 32.6 inches
    • 275/70/R18 - 33.2 inches
  • 20-inch rims
    • 275/60/R20 - 33 inches
    • 285/60/R20 - 33.5 inches
  • 22-inch rims
    • 275/50/R22 - 32.8 inches
    • 285/50/R22 - 33.2 inches

Of course, not all tire manufacturers follow the exact tire measurements and tread patterns. Furthermore, the tire's actual sizes may differ from their published sizes.

It is best to bring your truck to a professional tire shop to test which tires will fit.

Biggest Tires On Stock AT4

On the other hand, the GMC Sierra's trail-ready trims can accommodate more aggressive upsizing options. With a 2-inch factory front lift and off-road suspensions, the AT4 and AT4X can accommodate tires up to 34.8 inches in overall diameter.

Here are some of the possible tire sizes that you can choose for upsizing based on the rim size and model year of the GMC Sierra AT4 and AT4X:

  • 17-inch rims
    • 255/85/R17 - 34.1 inches
    • 34 x 10.5 / R17 - 34 inches
  • 18-inch rims
    • 285/75/R18 - 34.8 inches
    • 295/70/R18 - 34.3 inches
  • 20-inch rims
    • 285/65/R20 - 34.6 inches
    • 275/65/R20 - 34.1 inches
  • 22-inch rims
    • 285/55/R22 - 34.3 inches
    • 295/55/R22 - 34.8 inches

Again, these published sizes may not be exact for all tire manufacturers. Although these sizes are helpful guides, always test the fit of the actual tire first before buying a whole set.

How Do You Read A Tire Code?

Although your tire walls provide their size specifications, some of these numbers may not be readily decipherable. For example, let's use one of the GMC Sierra 1500's stock tire sizes: 285/65/R18.

  • 285 is the tire's tread width in millimeters.
  • 65 is the tire's aspect ratio in percentage form, meaning that the tire's sidewall height is 65% of the tire's tread width.
  • R18 means the tire has radial construction and should mount perfectly on an 18-inch wheel or rim.

What Is The Overall Diameter Of A Tire?

close-up of summer tires, fuel efficient car tires in auto service shop, represented for sale

A tire's overall diameter is from two corresponding points on the outermost circumference.

We need to mount and inflate the tire properly on its appropriately-sized rim to measure this diameter. Moreover, the tire should not bear any load and be set on flat ground.

How Do You Determine Tire Tread Width?

After getting the overall diameter, we can also get a tire's width. Tire or tread width is the horizontal distance from one sidewall to the other.

What Does Tire Aspect Ratio Mean?

Before computing the tire's aspect ratio, we need to get the tire's height.

Tire height is sometimes known as the "width" of the sidewall, and we measure it from the rim's outermost point to the corresponding point on the tire's outer circumference.

Next, we divide the tire height by the width to get the tire's aspect ratio. To illustrate, an aspect ratio of 65 tells us that the tire's height is 65% of its width.

Is There A Benefit To Having Bigger Tires?

 Checking the condition of off-road tires

Although some van or crossover owners like to upsize their tires to give their vehicles a bigger or broader stance, bigger tires usually suit full-size pickups and SUVs better.

The benefits are not only aesthetic but also practical for specific performance requirements.

Higher Ground Clearance

Without any other modifications, bigger tires immediately result in higher ground clearance. Due to the increased clearance, you will also get the following improvements:

  • better fording depth
  • higher approach and departure angles
  • higher break-over angle

You will appreciate these improvements when you drive your truck over unfriendly terrains such as flooded streets or challenging off-road trails.

Improved Traction

Wider tires result in larger road contact patches and better road traction. Better traction improves your vehicle control when driving over slippery surfaces.

Better traction keeps your vehicle more planted during emergency cornering instances.

Improved Ride Comfort

Taller tires have broader sidewalls, leading to more flexing capacity. Sidewalls flex to absorb the bumps and vibrations from the road resulting in a more comfortable ride.

Are Bigger Tires Better Or Worse For Your Vehicle?

Although bigger tires present several advantages, they also come with some trade-offs. Here are a few examples:

  • More expensive - bigger tires cost more than smaller tires
  • Less acceleration - heavier and wider tires cause more rolling resistance
  • Heavier steering - larger contact patches increase friction, especially during dry steering
  • Worse fuel efficiency - bigger tires strain the engine slightly more, leading to higher fuel consumption
  • Inaccurate speedometer reading - vehicles with larger tires will move faster than what their speedometers are showing.

You can minimize these adverse effects if you stay within 3% of your vehicle's stock overall tire diameter. However, some manufacturers design their trucks to be ready for up to 15% upsizing.

How Much Is A GMC Sierra?

 Used GMC Sierra 1500 AT4 pickup truck.

The GMC Sierra 1500 comes in different trims, engine options, drive configurations, and cabin and bed types. Using all of these options, GMC allows its Sierra 1500 buyers to build their own trucks based on their needs and preferences.

GMC Sierra 1500 2WD Starting Prices

  • PRO
    • 2.7-liter turbo high-output engine with 8-speed A/T - $ 42,895
    • 5.3-liter Ecotec3 V8 with 10-speed A/T - $ 44,835
  • SLE
    • 2.7-liter turbo high-output engine with 8-speed A/T - $ 50,855
    • 5.3-liter Ecotec3 V8 with 10-speed A/T - $ 53,900
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T - $ 54,695
  • Elevation
    • 2.7-liter turbo high-output engine with 8-speed A/T - $ 52,695
    • 5.3-liter Ecotec3 V8 with 10-speed A/T - $ 55,740
    • 5.3-liter Ecotec3 V8 with 10-speed A/T, front bucket seats, and Electronic Precision Shift (EPS) - $ 56,360
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T - $ 56,535
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T, front bucket seats and EPS - $ 57,155
  • SLT
    • 5.3-liter Ecotec3 V8 with 10-speed A/T - $ 53,995
    • 5.3-liter Ecotec3 V8 with 10-speed A/T, front bucket seats, and EPS - $ 56,440
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T - $ 57,115
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T, front bucket seats and EPS - $ 58,110
  • Denali
    • 5.3-liter Ecotec3 V8 with 10-speed A/T, front bucket seats, and Electronic Precision Shift - $ 64,595
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T, front bucket seats and EPS - $ 66,395

GMC Sierra 1500 4WD Starting Prices

  • PRO
    • 2.7-liter turbo high-output engine with 8-speed A/T - $ 46,195
    • 5.3-liter Ecotec3 V8 with 10-speed A/T - $ 48,085
  • SLE
    • 2.7-liter turbo high-output engine with 8-speed A/T - $ 54,155
    • 5.3-liter Ecotec3 V8 with 10-speed A/T - $ 57,150
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T - $ 57,995
  • Elevation
    • 2.7-liter turbo high-output engine with 8-speed A/T - $ 55,995
    • 5.3-liter Ecotec3 V8 with 10-speed A/T - $ 58,990
    • 5.3-liter Ecotec3 V8 with 10-speed A/T, front bucket seats, and EPS  - $ 59,610
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T - $ 59,835
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T, front bucket seats and EPS - $ 60,455
  • SLT
    • 5.3-liter Ecotec3 V8 with 10-speed A/T - $ 57,095
    • 5.3-liter Ecotec3 V8 with 10-speed A/T, front bucket seats, and EPS - $ 60,165
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T - $ 59,540
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T, front bucket seats and EPS - $ 61,210
    • 6.2-liter Ecotec3 V8 engine with 10-speed A/T, front bucket seats, and EPS - $ 62,710
  • Denali
    • 5.3-liter Ecotec3 V8 with 10-speed A/T, front bucket seats, and EPS - $ 67,895
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T, front bucket seats and EPS - $ 69,695
    • 6.2-liter Ecotec3 V8 engine with 10-speed A/T, front bucket seats, and EPS - $ 71,195
  • AT4
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T, and EPS - $ 64,295
    • 6.2-liter Ecotec3 V8 engine with 10-speed A/T, front bucket seats, and EPS - $ 66,650
  • AT4x
    • 6.2-liter Ecotec3 V8 engine with 10-speed A/T, front bucket seats, and EPS - $ 78,295
  • Denali Ultimate
    • 3.0-liter Duramax turbo diesel I6 engine with 10-speed A/T, front bucket seats and EPS - $ 81,195
    • 6.2-liter Ecotec3 V8 engine with 10-speed A/T, front bucket seats, and EPS - $ 83,695

Wrapping Up

On stock 4th-generation Sierra 1500s, you can fit up to 32.5-inch tires without rubbing. Newer, 5th-generation Sierra 1500s can accommodate true 33-inch tires. Finally, stock Sierra AT4 and AT4X can fit up to 34.8-inch tires.

Thank you for reading. We hope we were able to help you figure out the best tire upsizing option for your stock GMC Sierra 1500.

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