Tyre Pressure Advice

UK PROFESSIONAL DRIVERS FORUMS OWNER AND FLEET OPERATORS FORUM (INTERACTIVE)
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muckles:

newmercman:
Is it a 5yr best before date on tyres?

Didn’t actually find an age recommendation but more the effects of aging on tyres,

Generally tyres wear out before failure due to aging occurs. However, for vehicles or trailers that are only used occasionally (e.g. recreational vehicles) aging could be an issue. Since climate and exposure to sunlight affect aging, no date can be given at which a tyre expires. Recommendations for changing tyres range from 4 to 10 years. Aging may be observed by cracks on the tyre surface. However, according to NHTSA, tyres are primarily degrading from the inside-out, due to permeation and reaction of the pressurised oxygen within the tyre structure, with rates proportional totemperature. Cracking can eventually cause the steel belts in the tyre to separate from the rest of the tyre

My experience of race transporters, which do low mileage, so never actually wear out the tread, is around the 5 to 6 year mark the cracking becomes noticeable,
which according to the stuff I’ve just read also means the tyres are less flexible and less able to withstand the deformation cause by hitting objects, not that I bounce them over kerbs, but plenty of other things like road imperfections which the tyres ride over at full speed.

Secondly tyre ageing can be a significant factor due to reduced heat resistance of the tyre, and also the resistance to impact with obstacles is reduced, as explained most clearly on the website of Bridgestone

There are three main mechanisms of tyre ageing. The first involves rubber becoming more brittle. Sulphur is used to link rubber molecules together during vulcanisation with the application of heat and pressure, giving the rubber its useful elastic properties and strength. As the tyre absorbs energy in the form of light, heat or movement the tyre continues to vulcanise. This ongoing vulcanisation causes the rubber to become stiffer and more brittle. The second mechanism of tyre ageing is oxidation involving oxygen and ozone from the air compromising the strength and elasticity of the rubber and the integrity of the rubber to steel bond. Basically heat and oxygen cause cross linking between polymer chains (causing the rubber to harden) and scission of polymer chains (leading to reduced elasticity).Thirdly, breakdown of the rubber to steel-belt bond will occur due to water permeating through a tyre and bonding with the brass plate coating on steel belts. This causes the steel to rubber bond to weaken leading to reduced tyre strength and reduced heat resistance. If compressed air used for inflation is not completely dry, tyre strength will be affected over time. Even unused tyres will become more brittle, weaker and less elastic with exposure to water, air, heat and sunlight.

I believe DVSA have some regs on tyres more than 10 years old, might use another Google free pass to find out. [emoji38]

Interesting, a lot more to it than it first appears. Luckily I have a few more vouchers.

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So last week I had a clear out and a mate took a bunch (9) of old tyres off my hands, 11R22.5 drive axle, Michelins of course, I was considering getting them capped, but then decided against it. They had been stood up in the shed for a couple of years and were around 5yrs old, a couple of them were almost new as they were replacements for a pair that got dragged down the road when the brakes had frozen on (not by me) my mate wanted them to send away for retreading.

Long story short, out of the 9, only 4 are any good, the sidewalls have cracked on the rest, luckily the two good ones are fine and my mate already has 4 he’s already had done. The tyre man said the cracking can be eliminated by laying them flat, rather than having them stood up and he advised my mate to put his recaps on rims asap and inflate them to their maximum recommended pressure to keep them as good as new.

Now this begs the question, if a tyre has a life of five years, how do recaps make sense? I can get a good three years out of a set of drive tyres, then another three years out of a Michelin recap. That makes six years!

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Tyres over 10 years old will be banned from HGV & PSV:

gov.uk/government/consultat … -and-older

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newmercman:
Now this begs the question, if a tyre has a life of five years, how do recaps make sense? I can get a good three years out of a set of drive tyres, then another three years out of a Michelin recap. That makes six years!

I don’t think I read anything that said tyres had a finite life of 5 years, one did say 4 to 10 years, I did say the tyres in on the low mileage work I do seem to be around the 5 year mark. Of the tyres we replaced this week, one was 6-7 old being a 2012 tyre the other 2 were 5-6 years old.

The tyres are exposed to the elements and are sat for long periods with weight on them; I can only assume this is worse for the tyre than being run enough to wear it out in 3 years

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Tyres have a shelf life of 5 years when stored correctly,a tyre dealer can sell you a 5 year old tyre as new