33-Inch vs. 285 Tires: Real Diameters, Fitment and Which Size Fits Your Truck

Search for “33-inch tires” for your truck or Jeep and you will quickly find listings for 285s mixed in with sizes like 33×12.50R17. Forum posts call a 285/70R17 a “33,” while tire shops quote it as a 32.7-inch tire. If you are trying to fill your wheel wells without rubbing, or you want to know whether two sizes will look and behave the same, the mismatch is confusing.

The short answer is that “33-inch” and “285” describe different things. One is an overall diameter, the other is a width in millimeters. Some 285 tires land very close to 33 inches tall, and some do not come close. This guide explains both sizing systems, shows the real diameters of the most popular 285 sizes, and covers the fitment, speedometer, gearing and load range questions you should settle before buying.

How this guide was put together: This guide is general information based on common manufacturer and industry guidance; your owner’s manual is the controlling source. Prices are typical ranges, not quotes. Checked on October 22, 2026.

Two Sizing Systems Describing the Same Tire

Flotation Sizes: Measured in Inches

A size such as 33×12.50R17 is called a flotation or “high-flotation” size, and it is common on light trucks, SUVs and off-road vehicles in the US. Every number is in inches:

• 33 is the nominal overall diameter
• 12.50 is the nominal section width
• R means radial construction
• 17 is the wheel diameter

Flotation sizes are easy to read because the height is printed right on the sidewall. The figures are nominal, though. Actual measured diameters vary by brand and tread design, and many 33-inch tires measure a fraction of an inch under 33 when mounted and inflated.

Metric Sizes: Width in Millimeters

A size such as LT285/70R17 follows the metric system used on most passenger cars, SUVs and pickups:

• LT marks a light truck tire (a “P” or no prefix indicates a passenger tire)
• 285 is the section width in millimeters
• 70 is the aspect ratio, meaning the sidewall height is 70 percent of the width
• R17 means radial construction for a 17-inch wheel

Notice what is missing: the overall diameter. To get it, you have to calculate the sidewall height and add it, twice, to the wheel diameter. That is why “285” alone tells you nothing about whether a tire is 33 inches tall. A 285/35R20 on the rear of a sports car and a 285/75R17 on a lifted pickup share a width and almost nothing else.

How to Calculate the Diameter of a 285 Tire

The formula is simple once you see it:

Diameter (in) = rim diameter + 2 × (section width × aspect ratio ÷ 25.4)

The aspect ratio is entered as a decimal, and dividing by 25.4 converts millimeters to inches. For a 285/70R17:

1. Sidewall height: 285 × 0.70 = 199.5 mm
2. Convert to inches: 199.5 ÷ 25.4 = 7.85 in
3. Double it (top and bottom of the tire): 15.71 in
4. Add the wheel: 15.71 + 17 = about 32.7 in

Apply the same math across the common truck sizes and the “is a 285 a 33?” question answers itself.

For comparison, a true 33-inch tire has a circumference of about 103.7 inches and turns roughly 611 times per mile. The 285/70R17 and 285/75R16 sit within about a third of an inch of that figure, which is why the off-road world treats them as “metric 33s.” A 285/75R17, on the other hand, is closer to a 34-inch tire and needs more room than a 33×12.50R17.

A tire’s size code only gives a calculated diameter. Real tires vary by manufacturer and tread pattern, so check the published overall diameter for the exact model before you buy.

Width: Where a 285 and a 33×12.50 Really Differ

Height is only half the comparison. A 285 mm section width works out to about 11.2 inches. A 33×12.50 tire is nominally 12.5 inches wide, or about 317.5 mm, so it is roughly 1.25 inches wider. The nearest metric widths to a 12.50 flotation tire are the 305 and 315 sizes, and a 305/70R17 measures about 33.8 inches tall, while a 315/70R17 is about 34.4 inches.

That width difference matters in several ways:

• Clearance: Wider tires are more likely to rub on the upper control arms, frame, sway bar or inner fender liner at full steering lock, especially with stock wheels.
• Wheel width and offset: Section width is measured on a specific rim width, and wider tires generally want wider wheels. Changing wheel offset or backspacing to push the tire outward can cure inner rubbing but may create rubbing on the fender or bumper.
• Weight and rolling resistance: A wider, heavier tire takes more energy to turn, which usually costs some fuel economy and acceleration.
• Steering and stance: A wider footprint looks more aggressive and can help flotation on sand and mud, but it can also make steering heavier and increase tramlining on rutted pavement.

Will It Fit? Lifts, Leveling Kits and Rubbing

Most full-size pickups and SUVs leave the factory on tires in the 30- to 32-inch range. Stepping up to a 33-class tire usually means finding about an inch of extra radius, plus room for any added width.

Stock Height

Some vehicles accept a metric 33 with no suspension changes. The Jeep Wrangler Rubicon, for example, has come from the factory on LT285/70R17 tires. On many trucks, though, a stock suspension leads to rubbing on the front fender liners or valance when turning, or when the suspension compresses over bumps.

Leveling Kits

Many half-ton pickups sit lower in front than in back from the factory. A leveling kit raises the front, typically by around 2 inches, and that is often enough to clear a 285/70R17 or a similarly sized 33. Fit depends heavily on the specific model, wheel offset and tire width, so treat any rule of thumb as a starting point rather than a guarantee.

Suspension Lifts

A lift of roughly 3 to 4 inches gives more margin for 33×12.50 tires and leaves room for full suspension travel off-road. Lifts also change steering geometry, ride quality and sometimes driveline angles.

Before you commit, check fitment guides for your exact vehicle, then confirm clearance at full lock in both directions and with the suspension compressed. A tire that clears in the driveway can still rub when the truck flexes on a trail or hits a dip at highway speed. Our guide to plus-sizing tires and wheels explains the trade-offs of changing wheel sizes in more detail.

Speedometer Error and Gearing

Your Speedometer Will Read Low

The vehicle’s computer calculates speed from how many times the wheels turn. A taller tire covers more ground per revolution, so the speedometer and odometer read lower than your true speed. The error is proportional to the change in diameter.

A few miles per hour may not sound like much, but it adds up to speeding tickets and odometer readings that understate real mileage, which affects maintenance intervals and warranty records. Many trucks can be recalibrated with an aftermarket programmer or by a dealer, and doing so also helps transmission shift logic and some stability control functions work as intended.

Effective Gearing Gets Taller

A bigger tire works like a taller final drive ratio. Going from a 31.6-inch tire to a 33-inch tire on a truck with 3.73 gears makes the axle behave more like a 3.57 ratio. You may notice slower acceleration, more downshifting on hills and reduced towing performance.

For most modern pickups with eight- or ten-speed automatics, a 33-class tire is a manageable change, and regearing is rarely necessary at this size. The case for new ring and pinion gears grows when you go to 35-inch tires, tow heavy loads regularly, or drive an older vehicle with fewer gears and less power.

Load Range and Construction

Tire size tells you how big a tire is, not how much weight it can carry. That comes from the load index and, on LT tires, the load range.

• Flotation tires are almost always LT construction, commonly in load range C, D or E. Higher load ranges carry more weight at higher pressures and resist punctures better, but they ride more firmly.
• Metric 285 sizes come in both passenger (P-metric) and LT versions. Many all-terrain and mud-terrain models in 285/70R17 are sold as LT tires in load range C or E. The “XL” (extra load) designation applies to passenger tires, not to LT load ranges.

Never choose a replacement with a lower load capacity than your vehicle’s original tires, and match the load range to how you use the truck. A three-quarter-ton truck that tows a camper needs a different tire than a half-ton weekend trail rig. Remember that an E-rated tire usually requires adjusting inflation from the placard figure based on the tire maker’s load and inflation tables. Our guide to tire load range explains how to read these ratings.

Speed ratings on 33-class off-road tires tend to be modest. Ratings such as Q, R, S and T (99, 106, 112 and 118 mph) are common on all-terrain and mud-terrain designs, which is adequate for legal highway driving.

Performance: It Depends on the Tire, Not the Label

Tread design and construction drive performance more than the size label does: a 285/70R17 all-terrain and a 33×12.50R17 all-terrain behave far more alike than a 285 all-terrain and a 285 mud-terrain. Still, size has predictable effects:

• Width: The wider 12.50 tire offers a broader footprint for sand and soft mud, but it adds weight, rolling resistance and steering effort.
• Sidewall height: Tall sidewalls on 16- and 17-inch wheels let you air down on trails so the tire conforms to rocks and absorbs impacts. They also cushion potholes on the road. A 285/60R20 gives you 33 inches of height with a noticeably shorter sidewall, so it rides firmer and offers less protection off-road.
• Tread pattern: Mud-terrain tires with large voids are louder on the highway and wear faster on pavement than all-terrain designs in either size.

If most of your driving is on pavement with occasional dirt roads, a 285/70R17 all-terrain is usually the more livable choice. If you spend serious time in mud, sand or rocks and have the clearance, a 33×12.50 or a taller metric size gives you more width and footprint to work with. Our all-terrain vs. mud-terrain comparison covers how each tread type handles both worlds.

Price and Availability

Both sizes are widely available in the US, with dozens of all-terrain, mud-terrain and rugged-terrain models from major brands. The 285/70R17 is one of the most common light truck sizes on the market, and 33×12.50R17 and 33×12.50R20 are staples of the off-road aftermarket.

Prices depend far more on the model, tread type and load range than on the sizing system. As rough ranges per tire:

• Value and mid-range all-terrain tires in 285/70R17: roughly $180 to $300
• Premium all-terrain tires in 285/70R17 or 33×12.50R17: roughly $280 to $400
• Mud-terrain and heavy-duty E-load tires in either size: roughly $300 to $500 or more, with 20-inch versions often at the top of the range

Wider 12.50 tires typically cost a bit more than the equivalent 285 model because they use more material. Budget for mounting, balancing and any lift, leveling, wheels or speedometer recalibration, since those extras can cost more than the price difference between tires.

Frequently Asked Questions

The Bottom Line on 33s and 285s

“33-inch” and “285” are not competing tire sizes. They are two ways of describing tires, and the overlap between them is narrow. Run the formula, or check the table above, and you will see that a 285/70R17 or 285/75R16 is the closest thing to a metric 33, while a 285/75R17 is nearly a 34 and a 285/55R20 is closer to a 32.

Choose a metric 33 such as the 285/70R17 if you want more height with easier fitment, lower weight and less risk of rubbing. Choose a 33×12.50 if you want maximum width and stance and are prepared for leveling or lifting, wheel changes and a bit more fuel consumption. Whichever you pick, confirm the model’s published diameter, match or exceed your original load capacity, and recalibrate the speedometer so the truck knows how big its new shoes really are.

Sources

Specs, warranty terms and prices were checked on October 22, 2026. Prices change often.

• NHTSA: Tires (tire safety, pressure and maintenance)

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