Why did my garage coating peel only where the tires sit?

That pattern almost always points to hot tire pickup on a coating that was not well adhered to the concrete. Hot tires soften the film and grip it, and where the bond underneath is weak, the coating comes away with the tire. A well-adhered, fully cured epoxy holds where a weakly adhered one lets go.

Are brown tire marks on epoxy the same thing?

No. Brownish marks that will not scrub off, on a coating that is otherwise intact, are usually plasticizer staining: chemicals from the tire rubber migrating into the surface. It is mostly cosmetic. Some topcoats resist it better than others, and lighter colors show it more.

Can a peeling garage floor be patched?

Patching around a peel rarely lasts, because the same weak bond usually runs under the rest of the coating. The loose material has to come off and the cause has to be found. Often the honest recommendation is removing the old coating entirely and beginning again on properly prepared concrete.

How long should I wait before parking on a new floor?

As long as the product's label says for vehicle traffic, which is longer than for walking and depends on the temperature. Parking early is one of the commonest causes of hot tire pickup, so ask for the vehicle date for your own floor when the work is finished.

Hot Tire Pickup and Coating Failures

Hot tire pickup happens when tires that are hot from the road soften a garage coating and bond to it, then pull it off the concrete as they cool and the car moves. It mostly strikes thin one-part paints, coatings that had not fully cured, and coatings over poorly prepared concrete. A strong bond to well-prepared concrete and a full cure are what prevent it.

It tends to go like this. A garage floor is coated in spring. It looked good all summer. Then one day the homeowner pulled in after a drive, and when they backed out the next morning, two neat rectangles of coating had come up with the tires and were stuck to the tread.

That is hot tire pickup, and it is one of the most common ways garage coatings fail. It is also one of the most preventable.

What is hot tire pickup?

It is what happens when tires that are hot from the road soften a floor coating and bond to it. As the tire cools and contracts, or the car moves, it pulls the coating away from the concrete. It mainly affects thin one-part paints, coatings that had not finished curing, and coatings that were never well adhered to the slab in the first place.

Why tires do this

A tire on a summer road in East County gets very hot, and so does the asphalt under it. Driving straight into the garage puts that heat directly onto the floor. Hot rubber is softer and slightly sticky, and it presses into the coating under the weight of the car.

Two things then happen. The heat softens the coating, especially a thin, softer film like a latex floor paint. And chemicals in the rubber called plasticizers start to migrate into the coating, which makes the rubber and the coating cling to each other. As the tire cools overnight it contracts, and when the car moves, the bond between tire and coating can be stronger than the bond between coating and concrete.

That last point is the key. Hot tires rarely pull off a coating that is gripping the floor firmly. They expose a weak bond that was already there.

Which coatings are most vulnerable

Thin one-part floor paints, which are relatively soft and build a thin film.
Any coating parked on before it cured. Even a good epoxy is soft for days after it looks finished.
Coatings over smooth, unground concrete, which never had much grip.
Coatings over an old sealer or paint, where the new layer is only as strong as the old one beneath it.
Thin kit systems, where the film is light and the preparation was often light too.

Reading a failed floor

When a garage coating fails, the floor itself usually tells you why. The most useful thing you can do is pick up a loose piece and look at the back of it.

Peeling only in the tire tracks, with clean bare concrete showing and a smooth back on the peeled piece. The coating never gripped the concrete. Classic hot tire pickup on a preparation problem.
Peeled pieces with a thin layer of concrete stuck to the back. The coating gripped, but the top skin of the concrete was weak, dusty or not ground off. Still a preparation issue, just a different one.
Blisters scattered across the floor, or a white haze under the film. That points to moisture coming up through the slab rather than to the tires. It is covered in our article on testing a slab for moisture.
Lifting that starts at the garage door edge and works inward. Water collecting at the threshold, or an edge that was not keyed in, is getting under the coating.
Peeling where a layer of old paint comes up with the new. The floor was coated over an existing coating that was not fully removed.
Brown or yellowish tire marks that will not scrub off, on an intact coating. Plasticizer staining. Mostly cosmetic, and more visible on light colors.
A broad yellow band near the door. Sunlight ambering an epoxy that has no UV-resistant topcoat.
A floor that stays soft or tacky long after it should have cured. Usually a mixing problem or a cure in conditions colder than the label allows.

Some floors show more than one of these at once, which is part of why a failed floor is worth looking at in person before anything is decided.

Why the heat matters more inland

In El Cajon, Santee and the slopes of Spring Valley, summer afternoons are long and hot, and many garages face straight into the low western sun. A car that has been on the freeway and pulls into a garage that is itself warm puts more heat into the floor than the same car would near the coast. A coating with a marginal bond is tested hardest here, and it is often in the first summer that it fails.

That is also why the cure period matters so much inland. A floor coated in the cool of spring and parked on too soon in the first warm spell is a floor at risk.

Fixing a floor that has failed

It is tempting to patch the two rectangles where the tires sit. Unfortunately, the weak bond that let those areas go usually runs under the rest of the floor too, and patches over it tend to fail at their edges. The honest repair starts with removing everything that is loose, testing how well the rest is holding, and finding the cause. In many cases that means grinding off the old coating entirely and preparing the concrete properly before a new system goes down.

How it is prevented

Prevention is the same list every time: choose a coating made to take vehicle traffic, prepare the concrete so the coating can bond deeply, confirm the slab is dry, apply within the temperature range on the label, and keep the car out until the vehicle-traffic date has passed. Each of these is covered in more detail in our guide to epoxy floor preparation.

If your garage floor is peeling, or you want a new one that will not, the epoxy floors page explains how the work is planned, and the El Cajon page covers what the inland heat does to coatings. Ask for a free estimate and Ebenezer will read the failure with you, explain the cause in plain terms, and tell you what it takes to put down a floor that stays down.