Rick's Free Auto Repair Advice

Tire dry rot — causes

What causes tire dry rot?

Dry rot has many names but the same causes

If your tires have cracks in the sidewall, shoulder area and between the tread blocks, chances are you have tire dry rot. Tire cracks are also referred to as Sidewall Weathering, Weather Checking,  Weather Cracking, or Ozone Cracking.

tire cracks

#1 Cause of dry rot tire cracking

Prolonged exposure to the sun’s UV rays. UV degrades rubber and the synthetic materials used in your tires. To determine if the tire cracks are caused by sun exposure, simply compare the amount of cracking on the sidewall and shoulder outside of the tire to the shoulder and sidewall of the inside tire that isn’t exposed to the sun. If there are no cracks on the inside, then the damage was caused by UV exposure OR damage caused by the use of tire dressings.

#2 Cause of tire cracks — Tire damage from tire dressing

Tire dressing makes your tires shine. But if the tire dressing product you use contains any petroleum based products, you’re getting a shine at the cost of reduced tire life. Read the ingredients. If you don’t understand what the chemicals are, do a search for the product’s safety data sheet (SDS). If the product contains any petroleum distillates or petroleum byproducts, don’t use it on your tires.

The only acceptable tire dressing product is one that uses silicone. Silicone won’t degrade your tires.

#3 Cause of tire cracks; driving on underinflated or overloaded tires

When you drive on underinflated tires, you cause the tire shoulders and sidewalls to flex more than when they’re properly inflated. That extreme flex causes the rubber to heat up, and the heat degrades the rubber.

The same applies to tires that are driven when overloaded; they generate too much heat.

#4 Cause of dry rot — storing tires in high temperatures

If you store extra off-season tire in your garage in the summer, you can dramatically reduce their useful life. Heat is the enemy of all tires.

#5 Cause of tire cracks, long periods of non-use

All tires contain an anti-aging additive that’s activated by driving. If you don’t use your vehicle very often, the anti-aging additive can’t do it’s job and your tires will actually age faster.

#6 Cause of sidewall cracks — storing tires near ozone

All electric motors, battery chargers, generators and welding equipment generate ozone during their use. If you store your vehicle or your tires in areas where motors, battery chargers, generators or welders are operating,  you’ll reduce the life of your tires.

Do you have to replace cracked tires?

If the cracks are plentiful, as opposed to a few random, you should plan on replacing your tires soon.

Cracks in the tire tread voids. If the cracks in the tire tread voids are deep and penetrate down to the tires belts, you must replace the tires immediately. These cracks let water into the inner portion of the tire, causing corrosion and rapid belt wear, leading to catastrophic failure.

Is dry rot covered by the tire warranty?


Tire manufacturers’ warranties typically cover cracking for a period of 4 years from the date the tire was purchased or four to six years from the date the tire was manufactured.

But there are conditions to the warranty:

First, the tire dealer will inspect the tire for signs of poor maintenance like driving with underinflated tires, driving on the tire while it was flat. The dealer will dismount the tire and look for signs of abnormal wear on the inner liner that indicates under inflation or driving while flat.

They’ll also look for sidewall abrasion— signs that you scrape the tire against the curb.

©, 2021 Rick Muscoplat

Posted on by Rick Muscoplat


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