Keep mowing with thorns in the tyre - Puncture protection options for pneumatic tyres

The legendary flat tyre has been annoying drivers since 1887, the year John B. Dunlop invented the first air-filled tyre. Since then, everyone has been enjoying the air-filled tyre’s advantages: low weight, good traction, high speeds and, above all, high suspension comfort.

When using lawn tractors and ride-on mowers, it’s usually the small, nasty thorn that suddenly brings speedy mowing to an end – goodbye to your daily goal.

Small cause, but big effect: Lift the machine, remove the wheel, drive to the nearest dealer.

Once there, ask if he could fix it right away despite a full shop, wait 20 minutes, pay 20 to 30 euros for the repair and then quickly return to your work. Put the tyre back on and off you go. If all this together takes only one hour, you have been really lucky. You can guess what this downtime costs a service provider. So, hopefully nothing will happen for a while.

It’s good to hope, but if this happens two or three times a week, you’ll be looking for ways to protect yourself for cost reasons and to spare your nerves.

What options are available nowadays?

The first thing that comes to mind here are various puncture aids. These are products, mostly in the form of a spray can, which are carried in the car instead of the good old spare wheel and are available at every petrol station. In the case of a defective tyre, the agent is supposed to make the tyre drivable again by a chemical reaction and adhesive effect. Application is therefore not possible as a preventive measure but only in the case of an acute puncture. Almost always, this type of repair is not permanent, but only short-term. After repeated use, the tyre can even become unusable and must be replaced.

However, there are also permanent puncture protection products. These are filled into a tyre as a preventive measure, sealing the tyre immediately in the event of a puncture and thus enabling work to continue without downtime. Compared to short-term puncture aids products, these are able to permanently seal leaks and injuries and allow use of the tyre as usual. The way permanent puncture protection products work is simple but amazing. Either rubber particles or synthetic fibres of different sizes or lengths are added to a water-based, solvent-free fluid.

In the event of mechanical damage to the tyre, the tyre pressure presses the fibres or rubber particles into the puncture channel and blocks it mechanically and permanently. This functional principle is permanent and can be repeated as often as required. Only a small amount of air escapes until the puncture is closed by the puncture protection product. The special feature of this puncture protection is that thorns, nails or other sharp foreign bodies can get stuck in the tyre casing and still be sealed permanently.

One such puncture protection product is, for example, “Plattfuss-Stop” by the company AS-Motor in Bühlertann. At the Demopark 2019 trade fair, booth visitors were able to puncture a ride-on mower tyre with a pointed tool. After three days of trade fair and more than 200 holes, the tyre was still tight. AS-Motor became aware of the puncture protection agent at a fair in America. For a long time, many customers of the Swabian manufacturer of high grass mowers complained about frequent flat tyres.

An attempt to solve the problem by permanently foaming the tyres with polyurethane failed. Although permanent foaming prevents flat tyres 100%, it is accompanied by three major disadvantages: First, the weight. The weight of a front wheel (4.80/4.00-8) of the AS 940 Sherpa 4WD XL, diameter approx. 40 cm, width approx. 10 cm, increases by a 7 kg when foaming. If all four tyres of the machine were to be foamed, including the large rear wheels (20×10.00-8), the additional weight of the machine would be about 64 kg! Including the driver, this can exceed the maximum permissible total weight of the machine. Secondly, the high price. The foaming of an AS Sherpa front wheel costs about 70€ at a specialised company. Third, the completely missing suspension comfort afterwards. The driver and the machine will permanently suffer negative impacts. The handlebars, axle bearings and axle suspension will soon wear out and so will intervertebral discs of the driver.

After extensive tests of the puncture protection product “Plattfuss-Stop” and solid references at the US Army as well as the Royal Mail in Great Britain, AS-Motor decided to import the product and use it in its professional ride-on flail mower AS 1040 YAK 4WD. According to AS-Motor, YAK professional customers are very satisfied without exception. Therefore AS-Motor Customer Service recommends all customers with punctures to use “Plattfuss-Stop”. In tubeless tyres the permanent puncture protection can develop their maximum protection effect by more than 95%. Punctures are reduced considerably in tubular tyres as well, though unfortunately not as well as in tubeless tyres. It may prove beneficial to replace tubular tyres with tubeless tyres and then consistently use tyre puncture protection. In the case of tubular tyres on welded rims, it may be required to replace the casing and the valve. In the case of major damage to the tyre flank, however, even a good puncture protection product is powerless.

The old rumour – preventive tyre sealants stick everything together when changing tyres – is no longer the case. “Plattfuss-Stop”, for example, is water-soluble, easy to wash off, non-toxic, with an unlimited shelf life, and biodegradable. The price per litre according to AS-Motor is approx. 37,00€ incl. VAT. The customer can find specialized trade partners and filling quantities on AS-Motor’s website. For an AS 940 Sherpa 4WD, about 3 litres of “Plattfuss-Stop” are sufficient according to the manufacturer: 1 litre per rear wheel and 0,5 litre per front wheel. AS-Motor releases the product only for agricultural purposes, not for cars, motorcycles or similar.


The one-time investment in a puncture protection product when buying a new ride-on mower can be worthwhile – think of your wallet and your own nerves.

How the tire sealant AS-Motor Plattfuss-Stop works

1 Standstill

2 Drive

3 Foreign object penetration

4 Effect “Plattfuss-Stop”

5 Insertion of foreign object

6 Effect “Plattfuss-Stop” (with foreign object remaining)