What Size are My Trailer Wheel Bearings?

Time for some trailer bearing TLC? An integral part of trailer maintenance safety, you’re wise to stay on top of this task. Luckily, determining the right trailer wheel bearing size is not too difficult. In fact, accessing the necessary information is part-and-parcel of the trailer bearing replacement operation.

Steps for Determining Trailer Wheel Bearing Size

Bearings are comprised of 2 parts: the cup and the cone. The cup presses into the hub, the cone contains the rollers. These are not replaced independently but as a set. The hub holds 2 bearings, the inner bearing (inside the hub flange, closest to the trailer center), and the outer bearing. Since one size trailer wheel bearing does not fit all, to determine the correct size wheel bearing for your trailer, you’ll have to take apart the hub. Here’s how:

1. Support your trailer with a jack.
2. Take off the wheel and tire.
3. Remove the grease cap, cotter pin, and washer.
4. Remove the spindle nut.
5. Take out the hub itself.
6. Look for the part numbers on the inner and outer bearings to determine the correct trailer wheel bearing sizes.

Can’t Find Any Numbers?

If you can’t find or can’t read the numbers stamped on the bearings, you’ll have to take a few measurements. For this you need a digital caliper – a ruler or tape measure will NOT cut it. Using a digital caliper, measure both bearings and the spindle. Be sure to locate the brand of the axle and ATM (aggregate trailer mass) of the trailer, noting whether your trailer is for land-loving hauling or marine use. This will help your local parts distributor find suitable replacement parts. Axle size determines bearing size, which must be rated correctly for the load your hauling.

Lost in the Sauce?

If you’re confused, it’s probably best to enlist the help of a trusted local mechanic. After all, trailer bearings are essential to getting you and your load where you’re going safely. Ainsworth will get you there, providing A+ BBB and 5-Star Google-rated services. Contact us for a competitively-priced complimentary estimate today.