SHOULD YOU CONSIDER NITROGEN IN TYRES?

Tyres and correct load carrying pressures have been a constant consideration for Jeanette and I from day one of towing a caravan around the country.

Checking tyre pressures is regular routine.
The consistent finding is that from a 7am cold pressure reading of 45lb/sq.in. the lunchtime reading will be around 55lb/sq.in. in the warmer climates, and sometimes higher at end of days travel, which is generally when we have our “shake and rattle” problems, occurring to or inside the van.
This is often due to being on rough roads, even corrugated gravel roads towards the end of the day when the van tyres have increased to very high pressure.

If we attempt to compensate for the increase by starting the day with lower pressures, we are then “under inflated” damaging the tyres, and compromising safety, but also the under inflated tyres build up greater heat which softens the rubber and is also detrimental to tyre life.
When tyres are run at, near, or over their rated load or speeds, heat related damage occurs quickly.

The Scout tyres are also subject to significant pressure fluctuation but the driver and passengers more easily monitor the effects by changes in steering, body roll, jarring over potholes etc. Also if justified air pressures are more easily changed on the vehicle than on the van.

The heating and increase in pressure are caused by moisture contained within the compressed air and the accelerated deterioration of the tyres is caused by that moisture combining with the oxygen also contained in the compressed air. The subsequent oxidation process penetrates the lining eventually reacting with the rubber molecules breaking down the bonding, and also affecting the steel wires.
This entire process is often referred to inaccurately as “Tyre fatigue”.

We very rarely use compressed air from Service Stations, however our rims are rusted when we replace tyres, and have to be cleaned up to ensure a seal for tubeless tyres, proving how much moisture has been added within the compressed air.

Aluminium rims are also affected by the oxidation creating aluminium hydroxide, which gives an extremely fine dust that is noted for blocking tyre valves, causing them to not seal properly.

There is a view amongst tyre engineers that the problem of low tyre inflation could be solved by using Nitrogen to inflate tyres. Nitrogen is dry containing no moisture. It is an inert gas, so rust will not form as there is not oxygen or moisture, so no oxidation forms on the wheel.

If it were practical to remove the moisture from compressed air, making it “dry air” the tyres would run cooler than tyres filled with “normal” compressed air. However, “dry air” will still bleed through inner liners and tubes at the same speed as normal compressed air.

Unfortunately equipment to vacuum the compressed air from the tyre is not available, so deflating a tyre already pumped up with compressed air would not remove all the compressed air, prior to filling with Nitrogen.

There is a tyre outlet in Geelong that offers the option of having new tyres inflated with Nitrogen instead of normal compressed air, and although I don’t consider it practical for our four wheel drives I do think it is well worthwhile when fitting new caravan tyres, although I am aware that they would still have a small percentage of atmospheric air still trapped in with the Nitrogen.

There is quite a bit of reference information available if you have an interest in learning more.

Ken.