Trailer Grease Seal Sizes: Double Lip vs Triple Lip and How to Match a Seal by Number

The grease seal is the small ring pressed into the back of a trailer hub, behind the inner bearing. It rides on the spindle and keeps grease in and water, dirt and brake dust out. When a seal is torn, nicked, cocked in its bore or simply the wrong size, grease leaks onto the brakes and water gets into the bearings. Because a seal costs little and a ruined bearing or brake does not, the seal is the part to get exactly right every time a hub comes off.

This guide explains the three measurements that size a trailer grease seal, how double lip, triple lip and rubber coated seals differ, how to read a TruRyde seal number and a Dexter seal kit number, and how to measure when the old seal has no readable number. It covers trailer hubs from 2,000 lb. through 8,000 lb. axles, with a short section on the oil seals used on oil bath and heavy duty axles.

Key takeaways

• Three numbers size a seal. The shaft diameter (the seal's inside diameter, which rides on the spindle), the seal outside diameter (which presses into the hub bore) and the seal width. All three have to match the hub and spindle.
• The spindle sets the inside diameter. Measure the smooth seal area on the spindle, just behind the inner bearing. Do not guess from the axle capacity alone; several capacities share more than one seal size.
• Two sizes, one hub. Many 5,200 lb. to 7,000 lb. hubs share one hub bore but can use either a 2.125 in. or a 2.250 in. seal, depending on the spindle. Dexter notes its 12 in. x 2 in. hubs changed from a 2.12 in. to a 2.25 in. seal journal in October 1997.
• Double lip vs triple lip. In the TruRyde line, the triple lip seals have the same shaft diameter, bore, outside diameter and width as the double lip seal of the same size, so they fit the same hub. All TruRyde double lip and triple lip seals are spring loaded.
• Metal case or rubber coated. The outside of the seal decides how it is installed: Dexter recommends a thin coat of high temperature sealant on a metal case seal and a thin coat of oil, with no sealant, on a rubber coated seal.
• Replace the seal whenever the hub comes off. Dexter's maintenance schedule says to inspect seals for leakage and replace them if removed.

Terms used in this guide

• Grease seal: A ring with a metal or rubber coated outer case and one or more flexible rubber lips. It presses into the hub and seals against the spindle.
• Shaft diameter (seal ID): The inside diameter of the seal. It must match the seal area of the spindle.
• Hub bore: The machined hole in the back of the hub that the seal presses into.
• Seal OD: The outside diameter of the seal case. It is made to press tightly into the hub bore so the seal stays put.
• Seal width: The thickness of the seal from front face to back face.
• Seal journal: The smooth, ground section of the spindle the seal lips ride on, just behind the inner bearing.
• Spring loaded: A small coil spring (garter spring) wrapped around the seal lip that keeps it pressed against the spindle.
• Unitized oil seal: A seal used in oil bath hubs that seals inside itself, with its own sealing lips and a press fit on the spindle.
• Wear sleeve or wear ring: A thin stainless steel ring pressed over the seal journal to give the seal a new running surface.

The three measurements that size a grease seal

Every seal table in the TruRyde and Dexter catalogs lists a seal by the same few dimensions. Get these right and the seal will fit:

1. Shaft diameter. This is the number most seal names are built on, for example 1.719 in. or 2.250 in. It has to match the spindle's seal journal. A seal that is too small will be stretched and torn on installation; one that is too large will leak.
2. Hub bore and seal OD. On most sizes the seal OD is a few thousandths of an inch larger than the hub bore. For example, the TruRyde 1.719 in. double lip seal has a 2.565 in. OD for a 2.561 in. hub bore. That small interference is what holds the seal in the hub, so a seal for the wrong bore will either not go in or fall out.
3. Seal width. Seals for the same bore are not always the same thickness. The TruRyde 2.125 in. seals, for example, come in 0.313 in. and 0.375 in. widths.

On a spindle, the seal journal is the largest machined diameter behind the bearing seats. On TruRyde weld-on spindles, the catalog drawing shows it as the first step behind the inner bearing: 1.72 in. on the 3,500 lb. #84 spindles, and either 2.13 in. or 2.25 in. on the 7,000 lb. #42 spindles. Those two #42 versions even carry the size in their part numbers, ending in -213 or -225.

Double lip vs triple lip vs rubber coated

Grease seals for trailer hubs are sold in a few styles. Here is how they differ, using the TruRyde line Southwest Wheel carries as the example.

Double lip grease seals (metal case)

The standard trailer seal. A rubber sealing lip faces the grease, with a second lip behind it to keep water and dirt out. The outer case is bare metal, which presses into the hub. Lippert describes its double lip design as keeping water out for long-lasting performance. TruRyde double lip seals come in every common size from 1.250 in. through 2.250 in.

Double lip rubber coated grease seals

The same double lip design, but the outside of the case is covered in rubber instead of bare metal. In the TruRyde tables, the rubber coated seals list a slightly larger OD than the metal case seals for the same hub bore, for example 2.568 in. instead of 2.565 in. for a 2.561 in. bore. Install them with oil on the outside, not sealant (see the installation section below).

Triple lip rubber coated grease seals

A rubber coated seal with three sealing lips instead of two. In the TruRyde tables, each triple lip seal has the same shaft diameter, hub bore, OD and width as the double lip seal of the same size, so it goes into the same hub. Southwest Wheel carries TruRyde triple lip seals in the two most common sizes, 1.719 in. for 3,500 lb. axles and 2.250 in. for 8,000 lb. axles. Dexter also specifies triple lip seals in some of its own kits, including the 1.72 in. x 2.57 in. seal in its 3,500 lb. to 4,200 lb. Vortex hub and rotor parts, the 1.250 in. seal in its 2,500 lb. GAL-DEX galvanized idler hub kits, and the 2.250 in. seal in its 6,000 lb. GAL-DEX pre-greased E-Z Lube hub kit.

What they have in common

TRP lists the rubber on its TruRyde seals as a nitrile (Buna) compound of 70 durometer, and states that all of its double lip and triple lip seals are spring loaded. Whatever style you choose, the size still has to match: a triple lip seal is not a fix for the wrong shaft diameter or a scored spindle.

TruRyde grease seal sizes

These are the catalog dimensions for the TruRyde double lip grease seals. The spindle column uses the common spindle names: BT8 and BT16 for small 2,000 lb. and 2,500 lb. spindles, #84 for 3,500 lb. spindles and #42 for 5,200 lb. to 8,000 lb. spindles.

The rubber coated and triple lip versions use the same shaft diameters and hub bores:

For 6,000 lb. mobile home axles, TruRyde also offers a nylon mobile home grease seal, GS-1938NYL, for a 1.938 in. shaft.

How to read a TruRyde seal number

The TruRyde seal numbers spell out the seal. Take GS-1719DL:

The seal kits use a separate number. PP-GSK-1 through PP-GSK-5 are pre-packaged kits of two grease seals, one for each hub on a single axle, sized 1.250 in., 1.500 in., 1.719 in., 2.125 in. and 2.250 in.

TRP's catalog also prints a reference number for each seal, such as 171255TB for GS-1719DL and 171255TC for GS-1719DLR. In those tables the plain double lip seals carry reference numbers ending in TB and the rubber coated ones end in TC. If the number on your old seal looks like one of these, it can help confirm the size, but always check it against the shaft diameter and hub bore.

Dexter seal kits by brake and hub size

If your trailer has a Dexter axle, the Dexter service manual lists the replacement seal kit by brake size and hub, and the Dexter parts catalog gives each kit's seal size. Each of these kits contains two seals.

The service manual's table lists K71-303-00 for 10 in. x 2-1/4 in. brakes, and the Dexter parts catalog notes that K71-303-00 also fits the 10 in. x 1-1/2 in. hub. Dexter's note on the 12 in. x 2 in. hubs is the one to watch: the seal journal was 2.12 in. before October 1997 and 2.25 in. after. Same hub bore, same seal OD, different seal ID. That is why many 5,200 lb. to 7,000 lb. hub kits, including Dexter's 6,000 lb. and 7,000 lb. GAL-DEX and zinc coated hub kits and several TruRyde idler hubs, come with both a 2.125 in. and a 2.250 in. seal. Install the one that fits your spindle and set the other aside.

How to match a seal when the number is gone

Old seals often come out with the number worn off, or in pieces. Work from the spindle and the hub instead:

1. Check the axle and hub first. If the axle tag is readable, note the axle capacity and brake size. On a Dexter axle, the brake size points you to the seal kit in the table above.
2. Measure the seal journal on the spindle. Clean it and measure the smooth diameter just behind the inner bearing seat with calipers. This is the shaft diameter the new seal must match, for example 1.719 in. or 2.250 in.
3. Measure the hub bore. Measure the hole in the back of the hub where the seal sat. Compare it with the hub bore column above, for example 1.983 in., 2.561 in. or 3.371 in.
4. Measure the width of the old seal if you have it. This separates seals that share a bore, such as the 0.313 in. and 0.375 in. 2.125 in. seals.
5. Watch the close sizes. On 3,500 lb. #84 spindles, TruRyde offers both a 1.687 in. and a 1.719 in. seal for the same 2.561 in. bore. On 5,200 lb. to 7,000 lb. #42 spindles, the choice is 2.125 in. or 2.250 in. Measure; do not guess.
6. Match the bearings at the same time. Seal size and bearing numbers go together. If you are replacing bearings too, see Trailer Hub Bearing Adjustment and Grease, Step by Step, and consider a TruRyde bearing and race kit, which includes the grease seal.

Inspect the spindle before you install a new seal

A new seal will not stop a leak if the surface it rides on is damaged. The Dexter service manual says to clean the seal journal and inspect it for nicks or roughness, file any burrs from the leading edge or shoulder, and clean the journal with very fine emery cloth. Deep gouges or scratches there may cause the seal to fail and leak grease out of the hub. Also clean the seal bore in the hub and check it for nicks, gouges or scratches.

If the journal is grooved, a stainless steel wear sleeve can give the seal a new surface. Dexter offers optional stainless steel wear sleeves for the grease seal journal on certain axle capacities, and TRP lists stainless steel wear rings sized for BT, #84 and #42 spindles.

How to install a trailer grease seal

These steps follow the Dexter service manual for 600 lb. to 8,000 lb. axles:

1. Remove the old seal correctly. Pry it out with a seal removal tool or a screwdriver. Never drive the seal out with the inner bearing, which can damage the bearing.
2. Prepare the outside of the seal. On a metal case seal, apply a thin coat of high temperature sealant, such as Permatex High-Temp Red RTV Silicone Gasket, to the outside, using only enough to coat it so none reaches the rubber lips. On a rubber coated seal, use no sealant; apply a thin coat of oil to the outside rubber instead.
3. Lube the lips lightly. A slight amount of lube on the inner rubber lips helps the seal slide onto the spindle.
4. Orient the seal. Many oil bath seals are marked AIR SIDE on the side that faces out of the hub.
5. Drive it in straight. Use a seal driver of the proper size that contacts the outer ring of the seal case. If you have no driver, use a clean block of wood. Drive the seal in evenly and straight, and never hammer directly on the seal.
6. Stop at flush. On 600 lb. to 8,000 lb. hubs, the seal is pressed flush with the back surface of the hub. It is never necessary to bottom it out. Driving it too deep can damage the seal and let it touch the inner bearing.
7. Check that it is flat. A proper installation keeps the seal flat in the hub within 0.010 in. A seal that is cocked in the hub is more likely to leak.

E-Z Lube and pressure greasing

If your axle has Dexter's E-Z Lube feature, two notes in the service manual apply directly to the seal. First, if the hubs are removed from an E-Z Lube axle, replace the seals before you lubricate the bearings; otherwise grease is much more likely to reach the brake linings. Second, Dexter strongly recommends against pneumatic grease guns, which can push grease in too fast, force it past the seal and in rare cases dislodge the seal. Pump slowly with a manual grease gun while rotating the hub. For more on the bearing systems, see Nev-R-Lube vs E-Z Lube vs Standard Dexter Bearings.

Oil bath hubs and heavy duty axles use oil seals

Grease seals are for grease packed hubs. Oil bath hubs and larger axles use unitized oil seals, which are a different part. TruRyde lists these pre-packaged oil seal kits, each with two seals:

Dexter's matching kits include K71-386-00 for its 7,200 lb. and 8,000 lb. unitized hubs (2.250 in. x 3.376 in.) and K71-387-00 for its 9,000 lb. and 10,000 lb. GD unitized hubs (2.875 in. x 3.88 in.). For 10,000 lb. heavy duty through 16,000 lb. Dexter axles built in June 2026 and later, Dexter has moved to a spindle mounted oil seal; see Dexter 9K to 16K Axles: What to Match Before Ordering.

Checklist before ordering

• Axle capacity and, on a Dexter axle, brake size
• Seal journal diameter on the spindle (shaft diameter)
• Hub bore diameter
• Seal width, if you have the old seal
• Grease or oil bath hub
• Style wanted: double lip, double lip rubber coated or triple lip
• Number of hubs: one seal per hub, or a two-seal kit per axle
• Bearing numbers, if the bearings are being replaced too

FAQ

How do I know what size grease seal my trailer needs?

Match three things: the shaft diameter (the seal journal on the spindle), the hub bore and the seal width. The seal number on the old seal, or the brake size on a Dexter axle, can point you to the right size, but measure the spindle to confirm.

Is a triple lip seal better than a double lip seal?

A triple lip seal adds a third lip. In the TruRyde line, the triple lip seals match the double lip seals of the same size in shaft diameter, bore, outside diameter and width, so either one fits the same hub. Dexter uses triple lip seals in some of its galvanized, Vortex and pre-greased hub kits. Either way, the size must match, and the spindle surface must be smooth.

Can I put a triple lip seal in place of my double lip seal?

Yes, when the shaft diameter, hub bore and width match. The TruRyde 1.719 in. and 2.250 in. triple lip seals share those dimensions with the double lip seals of the same size.

What is the difference between a rubber coated seal and a regular seal?

A regular double lip seal has a bare metal outer case. A rubber coated seal has rubber on the outside of the case. Dexter recommends a thin coat of high temperature sealant on a metal case seal and a thin coat of oil, with no sealant, on a rubber coated seal.

My 7,000 lb. hub kit came with two different seals. Which one do I use?

Many 5,200 lb. to 7,000 lb. hubs fit spindles with either a 2.125 in. or a 2.250 in. seal journal, so the kit includes both. Measure the seal journal on your spindle and install the seal that matches.

What does GS-1719DL mean?

GS is grease seal, 1719 is the 1.719 in. shaft diameter, and DL is double lip. It fits a 2.561 in. hub bore on a 3,500 lb. axle with a #84 spindle.

Can I reuse a grease seal?

Dexter's maintenance schedule says to replace seals if they are removed. Prying a seal out of the hub usually damages it, so plan on a new seal every time the hub comes off.

Is a little grease around the seal normal?

For Nev-R-Lube bearings, Dexter notes that a slight amount of grease weeping from the seal area is normal, while excessive leakage may point to a bearing problem. On any hub, grease on the brakes or the inside of the wheel means the seal needs attention.

Can I use a grease seal in an oil bath hub?

Use the seal specified for the hub. Oil bath hubs use oil seals, such as the unitized oil seals listed above, not grease seals.

References

• TRP International, LLC. Axle, Suspension and Frame Components catalog (2026): Double Lip Grease Seals, Double Lip Rubber Coated Grease Seals, Triple Lip Rubber Coated Grease Seals, Unitized Oil Seals, Nylon Mobile Home Grease Seal, Butt Weld Style Spindles, and Stainless Steel Wear Rings.
• TRP International, LLC. TruRyde Packaged Parts brochure (2026): Grease Seal Kits, Oil Seal Kits, and Bearing and Race Kits.
• Dexter Axle. 2,000 to 8,000 lbs. Axle Operation Maintenance Service Manual: Seal Inspection and Replacement, E-Z Lube Lubrication, Maintenance Schedule, and Seal Replacement Reference.
• Dexter Axle. Parts and Kits catalog: Hub Components, Seals.
• Dexter Axle. 2,000 to 8,000 lbs. Axle catalog.
• Dexter Axle Product Bulletins #473 (Vortex hub and rotor service parts), #482 (7K zinc coated idler hub kit), #493 (6,000 lbs. GAL-DEX hub kits), #495 (2,500 lbs. GAL-DEX idler hub kits), and #532 (10,000 to 16,000 lbs. spindle mounted seal).
• Lippert. Premium Axle Parts catalog: Grease Seals and Unitized Oil Seals.

Related guides

• Trailer Hub Bearing Adjustment and Grease, Step by Step
• Nev-R-Lube vs E-Z Lube vs Standard Dexter Bearings
• Trailer Axle Terms: A Plain-English Glossary
• How to Identify Your Old Trailer Axle and Order a Dexter Replacement
• Dexter 9K to 16K Axles: What to Match Before Ordering

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