5 Warning Signs Your Mack Granite Tires Need Replacing

Your Mack Granite is built for tough jobs—whether it's hauling construction materials, navigating rough worksites, or tackling long highway miles. But the toughest truck is only as reliable as the tires it rides on. Worn-out tires don’t just affect performance, they compromise safety, fuel efficiency, and traction, putting you and your load at risk. Knowing when to replace your semi-truck tires can prevent costly blowouts, unexpected downtime, and even accidents. Here are five clear warning signs that it’s time to replace the tires on your Mack Granite before they cause serious problems.

1. Tread Depth Is Below Safe Levels

Tire tread depth is one of the most critical indicators of a tire’s health. The deeper the tread, the better the traction—especially in wet, icy, or uneven terrain. As the tread wears down, your tires lose grip, increasing the risk of hydroplaning and reducing braking performance.

The FMCSA (Federal Motor Carrier Safety Administration) requires that steer tires on commercial trucks have at least 4/32 of an inch of tread depth, while drive and trailer tires must have at least 2/32 of an inch. Driving on bald tires not only puts you at risk but can also lead to DOT fines and failed inspections. If your Mack Granite is running on low tread, replace those tires ASAP.

How can you check your tread depth? Try this simple trick:

• Use a tread depth gauge: A small, inexpensive tool that gives precise measurements.
• The penny test: Insert a penny into the tread with Lincoln’s head facing down. If you can see the top of his head, your tread is too worn, and it’s time for new tires.

2. Uneven Wear Patterns

Tires should wear evenly across the surface. If they don’t, it could indicate a serious alignment, suspension, or inflation problem. Uneven wear can lead to poor handling, vibration, and increased blowout risk. When you spot uneven wear, don’t just replace the tires—fix the underlying issue to prevent the new set from wearing out prematurely.

Look out for these common uneven wear patterns:

• Cupping or scalloping: High and low spots around the tread, often caused by worn-out suspension or shocks.
• Feathering: Tread wear that feels smooth on one side and sharp on the other, typically due to misalignment.
• Center wear: When the middle of the tire wears faster than the edges, it’s usually from overinflation.
• Edge wear: If the outer edges wear faster than the center, underinflation is likely the culprit.

3. Cracks, Bulges, or Sidewall Damage

Your Mack Granite’s tires take a beating every day—exposure to UV rays, extreme temperatures, chemicals, and road debris can cause visible damage to the sidewalls. Even if the tread looks decent, a cracked, bulging, or damaged sidewall is a serious hazard. Your first instance of symptoms or damaged sidewall may risk tire failure on the highway. It’s best to get a replacement before disaster strikes.

• Cracks and dry rot: Exposure to heat and sunlight can cause rubber to degrade, leading to cracks. If you see web-like cracks on the sidewall, it’s a sign that the rubber is weakening.
• Bulges or bubbles: These indicate internal tire damage, usually from hitting curbs, potholes, or debris. A bulging tire is at high risk of a blowout and should be replaced immediately.
• Deep cuts or gouges: Even small cuts can worsen over time, exposing the inner tire layers to damage.

4. Frequent Loss of Air Pressure

A slow leak may seem like a minor inconvenience, but it’s often a warning that your tire is failing. If you find yourself constantly refilling air, the problem could be more serious than just a puncture. Underinflated tires increase rolling resistance, making your Mack Granite burn more fuel and work harder. If a tire keeps losing air despite repairs, it’s time to replace it.

Common causes of air loss in truck tires include:

• Worn-out valve stems that leak air over time.
• Punctures from nails, screws, or debris that weren’t properly patched.
• Bead leaks—air escaping from the edge where the tire meets the rim.
• Sidewall damage that causes slow deflation.

5. Your Tires Are Past Their Lifespan

Even if your tires look fine, they don’t last forever. Most commercial truck tires are designed to last between three to six years, depending on mileage, road conditions, and maintenance. Older tires are prone to rubber deterioration, reduced traction, and increased risk of blowouts. When in doubt, replace aging tires before they become a liability.

You can fine tire life by checking the DOT date code on your tire’s sidewall. The tire sidewall will contain a four-digit number indicating the week and year the tire was manufactured. For example, "2219" means the tire was made in the 22nd week of 2019. If your tires are six years old or older, they should be replaced, even if they still have tread left. Also, if you use winter tires without replacing them in spring, they wear much faster due to the softer rubber that’s used. So it’s best to switch them out after winter. 

Protect Your Mack Granite with Proper Tire Care

Your Mack Granite’s tires are the only thing between your truck and the road, and neglecting them can lead to catastrophic failures, costly downtime, and even accidents. By staying ahead of these five warning signs—low tread, uneven wear, sidewall damage, air pressure loss, and tire age—you can maximize performance, safety, and efficiency.

At Franks Mobile Repair in Mechanicsburg, PA, we specialize in tire inspections, replacements, and emergency roadside services. If you’re unsure about your tires, give us a call—we’ll make sure your Mack Granite is running on safe, roadworthy rubber. For more information, read our article on why you should invest in high-quality tires.