Silverado 4500HD/5500HD/6500HD Maximum Speed Based on Axle Ratio

The 2019 Silverado 4500HD/5500HD/6500HD (Fig. 17) has a maximum vehicle speed that is based on the axle ratio of the truck. For example, if the truck has a 4.88 rear axle ratio, the truck will be limited to 65 mph. The speed limitation is operating as designed. There is no need to perform any diagnostics or replace any parts.


Fig. 17


The 2019 Silverado 4500HD/5500HD/6500HD Speed and axle ratios are:

  • Rear axle RPO 066, 4.10 ratio
    Maximum (Max) road speed: 78 mph
  • Rear axle RPO 092, 4.30 ratio
    Maximum (Max) road speed: 75 mph
  • Rear axle RPO 005, 4.56 ratio
    Maximum (Max) road speed: 70 mph
  • Rear axle RPO 008, 4.88 ratio
    Maximum (Max) road speed: 65 mph


To resolve top speed concerns on the 2019 Silverado medium-duty trucks only, the rear axle ratio (RAR) can be changed at the customer’s expense using GM parts for the rear gears and contacting the Techline Customer Support Center (TCSC) at 1-800-828-6860 (English) or 1-800-503-3222 (French) for an updated GM calibration.


Top Speed
Possible Rear Axle Changes
Change from: Change to:
4.88 4.10
4.88 4.30
4.88 4.56
4.56 4.10
4.56 4.30


There may be other concerns where a customer/dealer may want to change from a lower (numerical) RAR to a higher RAR to improve towing performance. The following changes apply only to 4×2 trucks. 4×4 trucks are equipped only with a 4.30 rear axle.


Towing Performance
Possible Rear Axle Changes
Change from: Change to:
4.10 4.56
4.10 4.88
4.30 4.56
4.30 4.88
4.56 4.88


TIP: 2019 Silverado medium-duty trucks are equipped with tires for the maximum road speed listed previously.


– Thanks to Richard Renshaw

2020 CT5 TAC Action Center
Unavailable Driver Assistance Features Messages

Leave a Reply

Your email address will not be published. Required fields are marked *