RC Car Tire and Wheel Sizes Explained: Dimensions and Size Charts

On most RC tires, the main size number is the wheel (bead) diameter in inches. A tire labelled 1.9 or 2.2 fits a 1.9-inch or 2.2-inch wheel. It does not tell you how tall the tire is. The outer diameter and the tire width are separate numbers, often listed in inches for crawlers and trucks and in millimeters for on-road cars and 1/8-scale buggies. Fitment also depends on the hex size, wheel offset and the space around the wheel. Compound names and replica full-size markings are not dimensions.

What do the numbers on an RC tire sidewall mean?

The numbers on an RC tire or its packaging usually describe four things: the wheel or bead diameter it mounts on, the overall tire diameter, the tire width, and the rubber compound. Not every tire shows all four. Many show only the bead size and a compound code. The full dimensions are often found on the manufacturer's product page or packaging rather than molded into the rubber.

Nominal wheel size: 1.0, 1.55, 1.9, 2.2, 2.8, 3.8

The nominal size of an RC wheel or tire is its bead diameter in inches. This is the diameter where the tire bead sits on the wheel. A 1.9 crawler tire has a bead diameter of about 1.9 inches (about 48.3 mm). It must go on a 1.9-inch wheel. Treat this number as a size class rather than a precise measurement. Matching classes matters more than measuring the bead to a fraction of a millimeter.

• 1.0 in is about 25.4 mm
• 1.55 in is about 39.4 mm
• 1.9 in is about 48.3 mm
• 2.2 in is about 55.9 mm
• 2.8 in is about 71.1 mm
• 3.8 in is about 96.5 mm

The bead size is the tire inner diameter at the mounting point, not the tire height. Two 1.9 tires can differ in outer diameter by more than half an inch.

Outer diameter and tire width

The tire outer diameter (also called outside diameter or OD) is the overall height of the mounted tire, measured from tread to tread through the center. It decides how tall the vehicle sits, how far the vehicle travels per wheel revolution, and whether the tire clears the body and chassis.

Tire width is the side-to-side measurement of the tire. Some product listings combine the numbers, such as an outer diameter given with the bead size. Read each value separately: one is the overall height, the other is the wheel it fits. Check the listing to see which unit is used. Crawler and monster truck tires are commonly described in inches. Touring car and 1/8 buggy tires are commonly described in millimeters.

Replica full-size markings on scale tires

Some scale crawler and truck tires carry molded text that copies real-truck tire sizes, such as 285/75R16 or 35x12.50R17. On an RC tire, this text is cosmetic. It describes the full-size tire being imitated, not the RC tire's dimensions or its wheel size.

You can still decode it to understand the look being copied:

• 285/75R16 means a 285 mm wide tire with a sidewall height of 75% of the width, on a 16-inch rim. The sidewall is 0.75 × 285 = 213.75 mm. The overall diameter is 16 × 25.4 + 2 × 213.75 = 406.4 + 427.5 = 833.9 mm, or about 32.8 inches. At 1/10 scale, that equals about 83 mm overall and a 1.6-inch rim.
• 35x12.50R17 means 35 inches overall diameter, 12.5 inches wide, on a 17-inch rim. At 1/10 scale, that is 3.5 inches overall and a 1.7-inch rim.

These scaled results will not necessarily match the real RC tire. A tire printed 285/75R16 may actually mount on a 1.9-inch wheel and have a different measured diameter. Always use the RC bead size and the listed RC dimensions for fitment.

Compound and other performance labels

Compound codes describe rubber softness or intended surface, not size. They appear as words (soft, medium, super soft), color dots, or brand-specific letters and numbers. Each brand uses its own system, so a code from one brand cannot be compared directly with another brand's code. Foam tires for on-road racing are often graded by shore hardness, where a higher number means a firmer foam. Other labels such as front or rear, belted, insert type, and pre-mounted describe construction or use. They affect grip and behavior, not the nominal size.

Dimensions, ratios, units and ratings: how to tell them apart

RC tire information falls into four kinds of values. Only dimensions and fitment specifications decide whether a tire fits.

Type of value	Examples	What it tells you	Used for fitment?
Dimension	Bead diameter 1.9 in; outer diameter 4.75 in; width 45 mm	Physical size of the tire or wheel	Yes
Ratio	75 in 285/75R16; sidewall height divided by width	Tire profile, meaning how tall the sidewall is relative to width	Indirectly, through the dimensions it produces
Unit	Inches, millimeters	How a dimension is expressed (1 in = 25.4 mm)	Only for converting and comparing
Performance rating	Soft, medium, shore hardness, brand compound codes	Rubber or foam hardness and intended surface	No
Mounting specification	12 mm hex, 17 mm hex, wheel offset	How the wheel attaches and where it sits on the axle	Yes

RC car tire size chart by vehicle type

Each RC vehicle category tends to use a common wheel standard. Model scale gives a hint, but it does not fix the tire size. Vehicles of the same scale can use different wheel sizes, so always confirm with your vehicle's specifications. The chart below lists typical pairings, not guaranteed fitments.

Wheel or tire size	Typical vehicles	Usual unit for listing	Notes
1.0 in	Micro crawlers (around 1/24 and 1/18 scale)	Inches	Small hubs; check the vehicle's hub type
1.55 in	1/10 scale crawlers with smaller, vintage-style tires	Inches	Smaller overall diameter than most 1.9 setups
1.9 in	1/10 scale trail and scale crawlers	Inches	The most widely used crawler wheel size
2.2 in	1/10 buggies, competition crawlers, some trucks	Inches	Buggy and crawler 2.2 tires share a bead size but differ greatly in diameter and width
2.8 in	1/10 stadium and monster trucks	Inches	Often sold pre-mounted for a specific hex size
3.8 in	1/8 monster trucks	Inches	Commonly 17 mm hex
1/8 buggy standard	1/8 nitro and electric buggies	Millimeters	Commonly 17 mm hex
1/10 touring	1/10 touring cars and drift cars	Millimeters	Commonly 12 mm hex; widths commonly 24 mm or 26 mm

RC crawler tire sizes

RC crawler tire sizes are named by bead diameter in inches: mainly 1.0, 1.55, 1.9 and 2.2, with larger formats such as 2.9 for bigger trucks. Within each class, the outer diameter varies widely. When comparing rock crawler tires, the bead size tells you which wheels fit. The outer diameter tells you how big the tire actually is.

RC crawler tire size chart

Crawler wheel size	Bead diameter	Typical application	What varies within the class
1.0 in	About 25.4 mm	Micro crawlers	Outer diameter, width, tread
1.55 in	About 39.4 mm	Scale crawlers with a classic, smaller-tire look	Outer diameter, width, tread
1.9 in	About 48.3 mm	1/10 scale trail crawlers	Outer diameter (commonly from just over 4 in to around 5 in), width, tread
2.2 in	About 55.9 mm	Competition and larger crawlers	Outer diameter, width, tread

RC crawler tire size comparison: same wheel, different tire

Two crawler tires on the same wheel size can differ in height, sidewall and rollout. Compare two 1.9 tires:

• Tire A: 4.75 in outer diameter on a 1.9 in wheel. Sidewall = (4.75 − 1.9) ÷ 2 = 1.425 in (about 36.2 mm). Circumference = π × 4.75 ≈ 14.92 in (about 379 mm).
• Tire B: 4.45 in outer diameter on a 1.9 in wheel. Sidewall = (4.45 − 1.9) ÷ 2 = 1.275 in (about 32.4 mm). Circumference = π × 4.45 ≈ 13.98 in (about 355 mm).

Based on geometry alone, Tire A raises the axle center by (4.75 − 4.45) ÷ 2 = 0.15 in (about 3.8 mm). It also travels 4.75 ÷ 4.45 ≈ 1.067 times as far per revolution, about 6.7% more. At the same motor speed and gearing, that means about 6.7% more ground speed. Tire A also has more sidewall to flex.

Now compare Tire A with a 4.75 in tire on a 2.2 in wheel. The sidewall is (4.75 − 2.2) ÷ 2 = 1.275 in. The overall diameter and circumference are the same as Tire A, so rollout and axle height are unchanged in theory. The difference is less sidewall and a larger, heavier wheel. A different bead size changes the tire profile, not necessarily the overall size.

1/8 buggy tire size and RC buggy tire sizes

1/8-scale buggy tires follow a shared standard that is usually described in millimeters rather than by an inch bead size. They typically measure roughly 83 to 86 mm (about 3.3 to 3.4 in) in outer diameter, are a little over 40 mm wide, and mount on wheels with a 17 mm hex. Exact figures vary by brand, tread and insert.

1/10 RC buggy tires usually mount on 2.2 in wheels with a 12 mm hex on many current vehicles. The front and rear tires differ: on two-wheel-drive buggies, front tires are much narrower than the rears. A 2.2 buggy tire and a 2.2 crawler tire share the bead size class but are very different tires. The wheel widths and shapes are designed for each tire type.

RC touring car tire sizes

RC touring car tires for 1/10 touring cars are usually described by width in millimeters, most commonly 24 mm or 26 mm. They mount on wheels with a 12 mm hex. The outer diameter of new tires is typically in the low-to-mid 60 mm range, but this varies by brand and type. Foam touring tires are often trued and shrink in diameter with use, so their actual size changes over time.

Touring wheels are also sold in different offsets. These change where the tire sits relative to the hub, without changing the tire size.

How do width, aspect ratio and rim diameter change tire size?

A tire's overall diameter equals the rim (bead) diameter plus two sidewall heights. Sidewall height can be expressed as a percentage of tire width, called the aspect ratio. These three values together set the outer diameter, and the outer diameter sets the circumference.

The basic formulas

• Outer diameter = bead diameter + 2 × sidewall height
• Sidewall height = (outer diameter − bead diameter) ÷ 2
• Aspect ratio = sidewall height ÷ tire width (× 100 for a percentage)
• Circumference (rollout per revolution) = π × outer diameter, with π ≈ 3.1416

Use one unit throughout. Convert inches to millimeters by multiplying by 25.4.

Steps to compare two RC tire sizes

1. Confirm both tires use the bead diameter that matches your wheels.
2. Find each tire's listed outer diameter and width, and convert to the same unit.
3. Calculate each sidewall height: (outer diameter − bead diameter) ÷ 2.
4. If you want to compare profiles, calculate each aspect ratio: sidewall height ÷ width.
5. Calculate each circumference: π × outer diameter.
6. Divide the larger circumference by the smaller to get the percentage change in distance per revolution.
7. Halve the difference in outer diameters to estimate the change in axle height.

Worked example: how width changes size at the same aspect ratio

Suppose two tires have the same 70% aspect ratio on the same 48.3 mm (1.9 in) bead, but different widths.

Tire width	Sidewall height (70% of width)	Outer diameter	Circumference
45 mm	31.5 mm	48.3 + 63.0 = 111.3 mm	About 349.7 mm
50 mm	35.0 mm	48.3 + 70.0 = 118.3 mm	About 371.6 mm

In this example, keeping the same ratio and making the tire 5 mm wider adds 7 mm to the outer diameter and about 22 mm to the circumference. If the ratio dropped instead, a wider tire could keep the same diameter. A width figure alone does not tell you whether a tire is taller.

RC tires are rarely sold with an aspect ratio printed on them. The ratio is mainly useful as a calculated comparison of how tall or low-profile two tires look and behave.

Calculated geometry vs actual RC tire dimensions

Calculated geometry is an idealized estimate. A real RC tire can measure differently, for several reasons:

• Listed sizes are nominal. Manufacturers may measure differently, and actual tires can differ slightly from the listing.
• Load and inserts change shape. Vehicle weight flattens the tire, so the loaded radius is smaller than half the outer diameter. Soft or firm foam inserts change how much it squashes.
• Speed can change diameter. Tires on fast vehicles can expand, or balloon, at high wheel speed. This raises the effective diameter.
• Wheel width changes the profile. The same tire mounted on a narrower or wider wheel can sit rounder or squarer.
• Tread and wear matter. Tall lugs, worn tread and trued foam all change the measured diameter.

Use calculations to compare tires and understand the direction and approximate size of a change. Confirm real clearance on the vehicle.

RC tire wheel compatibility: what has to match

A tire fits a vehicle only if the tire matches the wheel and the wheel matches the vehicle. Check these points in order:

1. Bead diameter: The tire bead diameter must equal the wheel diameter class, such as 1.9 to 1.9 or 2.2 to 2.2. Tires cannot be stretched onto a different bead size.
2. Wheel width: The tire should suit the wheel width. A tire much wider or narrower than its intended wheel may mount poorly or change shape.
3. Mounting style: Check whether the wheel is a glue-on or beadlock wheel, and that the tire bead suits that style.
4. Hex size: The wheel's hex must match the vehicle's wheel hex, such as 12 mm or 17 mm. Smaller and larger hex systems exist, and adapters are vehicle-specific.
5. Wheel offset: Offset is the distance between the wheel's mounting face and its centerline. Moving each wheel outward by a given amount widens the track by twice that amount in total. Too much or too little offset can cause rubbing on suspension, steering or links. Brands use different sign conventions, so check each listing's definition.
6. Clearance: A larger outer diameter or width must still clear the body, chassis, shocks and links through full suspension travel and steering lock.

If all six points check out, the tire and wheel are dimensionally compatible with the vehicle. Whether the size suits your driving is a separate question of gearing, handling and terrain.

How to measure an RC tire and wheel

Measuring confirms what a marking or listing claims. Calipers give the most consistent results.

1. Measure the mounted tire's outer diameter across the widest points of the tread, with no weight on the tire.
2. Measure the tire width at its widest point, including sidewall bulge if you need clearance figures.
3. For the wheel, identify the nominal size from its markings or listing. A rough measurement of the bead seat should be close to the nominal inch value.
4. Measure the hex across the flat sides.
5. Record all values in one unit, then use the formulas above to compare with another tire.