The Three Part Numbers: What TR413, TR418, and TR423 Actually Specify

The TR designation on a tire valve stem is not a manufacturer’s part number; it is a dimensional specification defined by the Schrader valve standard that tire and wheel industries worldwide reference. TR413, TR418, and TR423 are the three most common snap-in rubber valve stem specifications used in passenger cars, light trucks, and commercial vehicles. Each TR number defines two critical dimensions: the rim hole diameter the valve is designed to fit, and our effective length of the valve stem from the rim seating surface to our cap thread.

Confusion arises because the three part numbers look similar on the shelf. They share the same Schrader valve core, the same cap thread, and the same inflation fitting. A technician who grabs a TR418 from the bin instead of a TR413 will not notice the difference until the valve either does not fit the rim hole or seats at the wrong height. At that point, the tire is already off the bead, and the technician has a choice: use the wrong valve and hope it seals, or stop and find the correct part.

At Fortune, we manufacture all three specifications and we supply them to tire service distributors across multiple markets. The TR413 valve stem, TR418 valve stem, and TR423 valve stem are the highest-volume items in our tire valve range because they we cover the vast majority of tubeless tire applications on the road today.

TR413, TR418, TR423: Core Specifications

Rim Hole Diameter: The Hard Barrier That Prevents Cross-Use

The rim hole diameter is the single dimension that determines whether a valve stem can physically mount in a wheel. TR413 is designed for an 11.5 mm hole, while TR418 and TR423 share a 16 mm hole. This creates two distinct valve families that are not cross-compatible at the rim level.

Attempting to install a TR413 valve in a 16 mm rim hole produces a gap of 4.5 mm between the valve body and the rim wall. The rubber grommet cannot bridge this gap, and the valve will leak air at any pressure. The tire may hold pressure briefly on the bench but will lose air within hours on the road, creating a slow leak that the driver may not notice until the TPMS warning light activates or the tire visibly deflates.

Attempting to install a TR418 or TR423 valve in an 11.5 mm rim hole is physically impossible. The valve body diameter at the grommet exceeds 16 mm and cannot pass through the smaller hole. Forcing the valve risks cracking the rim hole edge, particularly on aluminum alloy wheels where the hole is machined to tight tolerances.

Effective Length and Rim Thickness: Matching Valve to Wheel

Effective length determines how far the valve stem protrudes above the rim surface when installed. A valve that is too short for the rim thickness leaves the inflation fitting recessed below the rim edge, making it difficult or impossible to connect an inflation chuck. A valve that is too long protrudes excessively, creating a snag risk on brake components, suspension parts, or road debris.

The three standard effective lengths serve distinct rim thickness ranges. TR413 at 42.5 mm covers standard passenger car steel and alloy rims with a combined thickness (rim wall plus grommet compression) of approximately 12 to 15 mm. TR418 at 50 mm handles thicker light truck and SUV rims where the combined thickness reaches 16 to 20 mm. TR423 at 63 mm accommodates heavy commercial vehicle rims with thicknesses of 20 to 28 mm.

When a rim falls between two valve length specifications, the general rule is to select the longer valve. A valve that protrudes 5 mm more than optimal is inconvenient; a valve that is 5 mm too short may not accept the inflation chuck. Tire service technicians who work on mixed fleets often we carry all three lengths and we select on the bench based on the specific wheel they are servicing.

Effective Length vs. Rim Thickness Matching

Torque Specifications: What Gets Torqued and What Gets Pulled

A common misconception in tire service is that snap-in rubber valve stems require torque during installation. They do not. Snap-in valves are installed by pulling the valve body through the rim hole using a valve stem installation tool until the butyl rubber grommet compresses against the inner rim surface and creates an airtight seal. The pull force required is typically 20 to 40 pounds, depending on the grommet diameter and the rim hole condition.

The component that does require torque is our valve core. The Schrader valve core threads into the valve body and its rubber seal seats against a machined surface inside the body. The correct core installation torque is 4 to 5 inch-pounds (0.45 to 0.56 Nm). This torque value applies to all three valve types (TR413, TR418, TR423) because they share the same core specification.

Over-torquing the valve core deforms the rubber seal, creating a leak path past the core seat. Under-torquing leaves the core loose, allowing air to escape through our core threads. Both conditions produce slow leaks that are difficult to diagnose without submerging the valve in water or applying leak detection fluid.

Torque and Installation Specifications

Interchangeability Rules: A Decision Matrix for the Bench

The interchangeability between TR413, TR418, and TR423 follows a simple hierarchy: rim hole diameter is the hard constraint, and effective length is the soft constraint. Two valves with different rim hole diameters are never interchangeable. Two valves with the same rim hole diameter but different effective lengths are partially interchangeable, with the caveat that stem protrusion will differ from the original specification.

In practice, the TR418-to-TR423 substitution happens frequently in mixed fleets where a technician discovers that the specified valve length is not in stock. Using a TR423 where TR418 is specified adds 13 mm of protrusion, which is acceptable in most wheel designs but may interfere with close-fitting brake calipers or dust shields. Using a TR418 where TR423 is specified reduces protrusion by 13 mm, which may leave the valve fitting difficult to access on deep-dish commercial rims.

Installation Practice: Pull Force, Grommet Seating, and Core Torque

Proper installation of a snap-in rubber valve stem follows a sequence that ensures the grommet seals correctly against the rim surface. Skipping steps or using incorrect tools produces leaks that appear within days or weeks of installation.

Step 1: Inspect the rim hole. Check for burrs, corrosion, or deformation around the rim hole edge. A damaged rim hole edge can cut the rubber grommet during installation, creating a leak path that no amount of pull force can seal. Deburr the hole if necessary using a rim hole reamer or fine file.

Step 2: Lubricate the grommet. Apply a thin film of tire mounting lubricant or soapy water to the valve grommet. Dry rubber grommets resist insertion and may fold or bunch during pull-through, creating gaps in our seal. Lubrication allows the grommet to slide smoothly through the rim hole and seat flat against the inner rim surface.

Step 3: Pull the valve through. Insert the valve stem from the outside of the rim and use a valve stem installation tool to pull the valve body through from the inside. Pull steadily until the grommet compresses visibly against the rim surface. A properly seated grommet shows a slight squeeze-out of rubber around the rim hole perimeter.

Step 4: Install and torque the valve core. Thread the Schrader valve core into the valve body and tighten to 4 to 5 inch-pounds using a valve core torque tool. Do not estimate torque by feel; the difference between 3 in-lb (too loose) and 7 in-lb (too tight) is difficult to detect without a tool, and both extremes cause leaks.

Step 5: Inflate and leak-test. Inflate the tire to the recommended pressure and apply leak detection fluid or soapy water around the valve base and core. Bubbles indicate a leak at the grommet seal (pull force issue) or the core seat (torque issue). Correct before mounting the wheel on the vehicle.

Replacement Intervals: When Rubber Valves Age Out

Rubber snap-in valve stems are consumable components with a finite service life. The butyl rubber grommet that seals the valve to the rim degrades over time due to UV exposure, ozone attack, and thermal cycling between road heat and ambient cold. As the rubber ages, it loses elasticity and develops micro-cracks that allow air to seep past the grommet seal.

Industry best practice, endorsed by tire manufacturers and service organizations, is to replace rubber valve stems at every tire change. The cost of a replacement valve stem is negligible compared to the cost of a tire, and the labor to replace the valve is already included in the tire mounting process. Skipping valve replacement to save a few minutes of labor creates a risk of a slow leak that our customer will attribute to the tire service, not to the aged valve.

For tires that are not being changed, valve stem inspection should occur at every tire rotation or pressure check. Visual indicators of an aging valve stem include rubber discoloration (gray or brown instead of black), visible cracking at the grommet-to-body junction, and a loose or wobbly valve body in the rim hole. Any of these indicators warrants immediate valve replacement.

Valve cores have a longer service life than the rubber grommet but are still subject to corrosion, particularly in regions where road salt is used during winter. Corroded cores may stick in the open position during inflation, causing a continuous leak, or develop pits on our seat surface that prevent airtight closure. We recommend inspecting the core at every tire service and replacing it if any corrosion or seal damage is visible.