This Is The Truth About Tire Sealant. ( Slime, Fix-A-Flat, Berryman, Flat Out, Tireject )

Test Setup and General Findings

The reviewer compared three aerosol products—Fix-a-Flat, Slime aerosol, and SMB Flatout—with four pour-in liquids—TireJect, Berryman Seal-R, Slime, and Flatout—plus Elmer’s school glue.

Products were tested in the same tires with a ¼-inch tread puncture, a screw near the tread edge, a utility-knife cut, and a tire with about 158 punctures. An additional test used a ½-inch hole. The reviewer manually dismounted and cleaned the tires between products.

All products handled the basic ¼-inch tread puncture, but the more difficult tests revealed major differences. In general, thicker sealants sealed better, though very thick products could be difficult or impossible to dispense through a tire’s valve stem.

Sealants can make tire changes messy, so the reviewer recommends telling a tire shop if sealant has been used. The tested products were generally water-soluble and could be rinsed out.

Product Results

1. Flatout by Multi Seal — Best Overall

• Best performance: Sealed the ½-inch tread hole and held well enough for the reviewer to drive 5 miles at 40 mph. It also handled the other tested punctures, including the heavily punctured tire.
• Main drawback: Extremely thick and fiber-rich; it clogged the valve stem within seconds. The reviewer had to break the tire bead and pour it directly inside.
• Best suited to: Tires that can be filled without relying on a modern passenger-car valve stem, such as those on some older vehicles or equipment. It is not a practical roadside fix for many modern cars.

2. Slime Liquid — Strong All-Rounder

Slime sealed the tested punctures, including the heavily punctured tire overnight. It sealed a ¼-inch open hole only after the reviewer repeatedly spun the tire for about two minutes. The reviewer described this result as borderline and messy. It could not seal the ½-inch hole.

Its flexible dispensing tube was easier to use than Berryman’s. The reviewer estimated its limit at somewhere around ¼–⅜ inch, noting that even the ¼-inch test was initially difficult to seal.

3. Berryman Seal-R — Good Sealing, Poor Dispenser

Berryman sealed the basic punctures and the heavily punctured tire. After sitting overnight, the heavily punctured tire had lost only about 3–4 psi.

It could not seal the ¼-inch open hole once the puncturing object was removed. The reviewer said it should work better if the object remains in the tire and is not hollow. Its rigid dispensing tube was hard to fit over the valve, and the packaging made it the messiest product in the test.

4. TireJect — Better as a Preventative Product

TireJect sealed the ¼-inch puncture, edge screw, and cut. However, it failed to keep the heavily punctured tire sealed while stationary: its thin formula ran down to the bottom, leaving upper punctures exposed.

The reviewer considered it more suitable as a preventative sealant than an emergency repair. Its low viscosity may help it flow around the tire and potentially affect balance less.

Aerosol Sealants — Not Recommended

Fix-a-Flat, Slime aerosol, and SMB Flatout sealed the basic puncture and edge screw. They also worked on the cut when it was positioned at the bottom of the tire. Fix-a-Flat and Slime tended to run out before sealing the cut; SMB Flatout performed somewhat better.

None was a good choice for the heavily punctured tire while it sat still, because the thin sealant drained away from upper punctures. The reviewer saw little overall performance difference among the three. He said Fix-a-Flat and Slime aerosol share the same sealing formula but use different propellants, while SMB Flatout was slightly thicker.

Inflation was inadequate: Fix-a-Flat added only about 1–2 psi and did not lift the tire off the ground, while SMB Flatout reached about 7 psi. The reviewer said an air compressor would still be needed to make the tire safely drivable.

The reviewer also raised a safety concern about SMB Flatout’s propane-butane propellant, particularly if a damaged tire and steel wheel were to create a spark. He noted that SMB’s can was 12 oz, compared with 14 oz for Fix-a-Flat.

All three aerosol products froze in the reviewer’s overnight freezer test. He speculated that their thinness may be related to water content and the need to pass through the valve.

Elmer’s School Glue — Not a Worthwhile Substitute

Elmer’s glue was too thick to dispense easily through the valve; the reviewer said it would need to be thinned with water. Once inside, it sealed the basic puncture, edge screw, and cut, but did not perform well on the heavily punctured tire.

It also froze in the freezer test. The reviewer recommends buying a purpose-made product instead of mixing glue and water.

Overall Verdict

For sealing ability, the reviewer ranked liquid Flatout first, followed by Slime, Berryman, and TireJect. Flatout’s thickness, however, makes it impractical to use through many modern passenger-car valve stems. Slime is the more practical strong performer among the top options, while Berryman seals well but is messy to dispense.

The reviewer advises against aerosol sealants for this purpose, especially when better-performing pour-in products and an air compressor are available.

Speaker Contribution

The video presents one reviewer’s testing and opinions; it includes no distinct alternate speaker viewpoints.