Part Number: A4138


Product Details

Wheel Bearing Cups and Cones 

FAA-PMA approved Timken wheel bearings for Goodyear, Cleveland, and McCauley wheels

  • Class 2 aviation grade FAA-PMA bearings (Timken designates these with a -20629 suffix)
  • Tighter tolerance and higher quality control than Class 4 automotive bearings
  • Save $$


Don't be tempted to buy cheapy automotive bearings

Because Timken uses the same part number for both the automotive and aviation versions of these bearings, many people mistakenly use the lower quality automotive bearings in their airplane. It is critical that the FAA-PMA Class 2 version be used for aircraft applications for two reasons:


  • They are a higher class of bearing with tighter tolerance and have been subjected to more stringent quality control procedures. Due to the smaller diameter of aircraft wheels, at a given ground speed the bearings rotate at a much higher RPM and require the tighter tolerances to prevent premature failure.

    Example: At a 70 mph touchdown speed (equivalent to highway speed of a car), a typical 17 inch diameter airplane tire is rotating at 1384 RPM, whereas a typical 27 inch car tire is only rotating at 871 RPM. So even though the aircraft bearing is only subject to intermittent use, some of the performance demands are much higher than a typical automotive application. 


  • It is a violation of FAA regulations to use non-approved automotive bearings on certified aircraft.


Wheel to Seal Kit and Bearing Cross Reference

Bearing Cup and Cone Dimensions


APS BlackSteel brake discs and linings, brake bleed valves, and wheel grease seals also available.

warningWARNING: Cancer and/or Reproductive Harm -

Eligible Aircraft

Make Series Model Beginning S/N Ending S/N Quantity Per Aircraft Location Comment Eligibility Chart
Cessna 180 180F 18051184 18051312
Cessna 180 180G 18051313 18051445
Cessna 180 180H 18051446 18052284
Cessna 180 180J 18052285 18052384
Cessna 180 180J 18052385 18052770
Cessna 185 185 185-0001 185-0237
Cessna 185 185A 185-0238 185-0512
Cessna 185 185B 185-0513 185-0653
Cessna 185 185C 185-0654 185-0776
Cessna 185 185D 185-0777 185-0967
Cessna 185 185E 185-0968 185-1149
Cessna 185 A185E 18501600 18502090
Cessna 185 A185E 185-0968 185-1599
Cessna 185 A185F 18502091 18502310
Cessna 185 A185F 18502311 18504448

Related Product Catalog Pages

Wheel to Seal Kit and Bearing Cross Reference