The Department of Transportation (DOT) has established many safety regulations for tires used on commercial vehicles.
Most importantly, your truck will be placed out of service (you can’t drive until the condition is fixed) if you have a tire that:
(1) Has body ply or belt material exposed through the tread or sidewall,
(2) Has any tread or sidewall separation,
(3) Is flat or has an audible leak, or
(4) Has a cut to the extent that the ply or belt material is exposed
DOT Steer Tire Regulations
The DOT steer tire regulations are a set of rules and guidelines that commercial vehicles must follow when it comes to their front, or steer, tires. These regulations help ensure that these tires are safe and reliable for use on the road.
One of the main DOT steer tire regulations is regarding the minimum legal tread depth.
According to the DOT in 49 CFR 393.75(b), “any tire on the front wheels of a bus, truck, or truck tractor shall have a tread groove pattern depth of at least 4⁄32 of an inch when measured at any point on a major tread groove”.
So, the DOT steer tire tread depth regulations say you must have a minimum tread depth of 4/32 inches of tread depth on your steer tires. This helps ensure that there is enough traction on the road in wet or slippery conditions.
Another important regulation relates to steer tire condition. Steer tires must also be free from any bulges, cuts, cracks, or other damage that could potentially cause a blowout while driving. Additionally, they cannot have any exposed cords or belts and the weight of the truck can’t exceed the amount listed on the sidewall of the steer tires.
The DOT steer tire regulations also prohibit the use of retreaded or regrooved tires in the steer tire positions of any bus, large truck or truck tractor.
DOT Trailer Tire Regulations
DOT Minimum Tread Depth for all trailer tires is 2/32 of an inch. So, all trailer tires should have at least 2/32 inch of tread wear remaining when measured in a major tread groove.
One of the most important DOT trailer tire regulations deals with size and load capacity.
The size of a trailer tire should match the specifications outlined by the manufacturer.
Overloading a tire can cause it to fail or blow out, which could lead to an accident.
It’s also important to note that different types of trailers have different weight limits, so each trailer owner must make sure they’re using appropriate tires for their specific vehicle.
Another important DOT regulation requires proper inflation levels for all DOT trailer tires.
Underinflated tires can cause excessive heat buildup and tread separation while overinflated tires can cause uneven wear patterns leading to reduced handling capabilities.
The DOT also mandates that all trailer tires be marked with speed ratings indicating maximum safe travel speeds as well as its recommended usage conditions such as weather and terrain type.
Tire safety is especially important for specialized haulers like car haulers or those hauling oversized or over-dimensional loads.
Operating on trailer tires that are overloaded or overinflated when carrying these loads can easily (and pretty quickly) catch fire.
DOT Tire Tread Depth Regulations
DOT tread depth requirements state that each of your steer tires must meet the DOT minimum tread depth of 4/32 of an inch. All other truck or trailer tires must have at least 2/32 of an inch to be within the minimum legal tread depth.
These DOT tread depth regulations can be found in 49 CFR 393.75(b) and 393.75(c).
Violations of 393.75(c) accounted for about 446,000 DOT violations over the last 5 years, so this should be a major fleet maintenance and DOT compliance concern.