Car & Bike When should one change car tyres?

[Renegade]

I was reading somewhere that tyres degrade over time even if they are low on mileage. A good rule of thumb which I thought was around 40K Kms. It was however recommended not to go at very high speeds on tyres which are more than 4 years old, as they have a good chance to blow due to the heat generated. And from the stories I have heard, blown tyres have been the most common reason for accidents on the Mumbai-Pune expressway.

On a related note I changed one of the tyres which was less than a year old and roughly 5K Kms because it had around 10+ punctures and was still leaking air. Didn't think it was safe to hit a Pune to Goa ride on that tyre.

 

[rdst_1]

Even I have changed tyres at around 25k kms. I just look at the condition of the tyres rather than at how much they have run.

 

[ankushv]

I drove my alto from 2004 to 2013 on the same set of tires . Had a total of 2 punctures in the 9 years I had the car . Never changed the tires as the tread was still there . But in hindsight I felt even if my usage was low I should have changed my tyres once every three to four years . Even when I sold my car the tires looked new as I drove my alro only 30k kms in 9years . Great car . I believe they were mrf zvts . Rubber hardens over time so better and safer to replace every three to four years m

 

[whatsinaname]

Go by tread wear, not by mileage. Most new tires have a tread wear indicator. If you see it, move to new tires.

If your alignment is not correct, you could get uneven wear. So check tread depth in different areas.

As for tires by age, it depends a lot on environmental conditions. Temperature, humidity, direct sunlight (i.e., parking location), etc. I think 6-10 years is usually the number thrown about. Old rubber goes dry and stiff and starts cracking. It should be easily noticeable.

 

[puns]

People who have driven for long know when tires are not performing well. Look out signs for brake pattern, acceleration, grip in rains etc.
One thing was told by my father years back, never change just 1 tyre. Either change both fronts, both rear or all 4 together but never just one. Not sure if its a myth.

 

[cranky]

Tyres should ideally be changed all at once or in sets of two.

Tyres should be rotated every 5k kms or 6 months.

Tyres should be changed at 4 years of age regardless of wear. Not more than 5. The rubber hardens and you lose comfort, pliability, shock protection and puncture resistance. Also hard tyres do tend to overheat.

The wear indicator on the tyre is designed to tell you when the tyre is too worn to continue. It.s a small bump in the tread groove, when the tread reaches that level you change. If the tyre is so worn that you can't see it, it's time to change.

If a tyre has more than 2 punctures, it is time to change. Converting tubeless to tubed tyres is Russian roulette.

Tyres should always be filled to correct cold pressure. Nitrogen tends to reduce time between fills, specially for cars that spend more time parked.

A visual inspection of tyres will tell you if you need new ones. Rubber tends to crack an split when it ages.

Replacing one tyre at a time will push the suspension out of balance as the grip on worn tires tends to be more than that on fresh tyres.

 

[manoja2k]

In the initial periods, I was driving my Alto with stock tyres. My driving was too less, around 22K in 4years. So there was hardly any wear. One day while driving on a highway @ around 80kmph, my rear tyre burst (odometer reading 22400kms). I had filled the tyre with air at the beginning of the journey, so it can't be pressure issue. Initially I thought it was because of heat, but since it was raining constantly and my tyre did not have a low pressure I don't think it was because of heat. I went to the tyre dealer and changed all the tyres into tubeless one. As per the dealer one should change the tyre either every 3years or 30000km or if there is excessive wear. He says with time tyres start aging and they become brittle. Brittleness results in tyre busrsts.

 

[Renegade]

Tyres should always be filled to correct cold pressure. Nitrogen tends to reduce time between fills, specially for cars that spend more time parked.

Are there any benefits or drawbacks of filling nitrogen in tires besides that you don't need to recheck that frequently.

 

[cranky]

Zilch. Ride comfort is slightly better but that has less to do with Nitrogen, than the consistency of pressure over say, a three-month period.

Are there any benefits or drawbacks of filling nitrogen in tires besides that you don't need to recheck that frequently.

 

[ssslayer]

Are there any benefits or drawbacks of filling nitrogen in tires besides that you don't need to recheck that frequently.

The air that we fill (and breathe) has about 80% nitrogen.
You cannot expect something radically different by filling 100% nitrogen.

Tubeless tyres hold their pressure for months with normal air.
Nevertheless one should make it a habbit to inspect the tyres everytime he embarks on a ride. (even to your neighborhood market)

 

[cranky]

Fair warning, I've worked for a few years with the technical team at Micehlin.

Here's how this works.

The oxygen molecule is significantly smaller than the nitrogen molecule. This is basic chemistry.

The oxygen molecules are small enough to escape through the rubber. This is the exact mechanism that air escapes in normal use. The nitrogen stays trapped longer but eventually it does escape too.

The thermal coefficient of nitrogen is much, much lower than oxygen. Pure nitrogen will retain volume about 10 to 12% better than air captured from the atmosphere.

10% of 30psi is 3psi, which is a typical figure for the gap between air and nitrogen when filling. In very hot and very cold climates, nitrogen is strongly recommended for. a more consistent pressure. Now you can choose to believe, not believe or look at pseudo science shows where it is proved that there is no difference.

Every racing franchise worth its salt uses nitrogen for tyres, because of the more stable pressure. Else it would take months to warm up the tyres.

Here's a link with some myth busters, in both respects. It's not magic, just simple compound chemistry taught in grade 7.

http://www.popularmechanics.com/cars/how-to/repair-questions/4302788

 

[Raghav_K]

I change every 40000 km usually....

And what's the problem with changing tubeless to tubed.. One of my tubeless tyres had a small hole in the side and couldn't be repaired, so i made it tubed, and use it as the spare tyre..

 

[cranky]

A better way to ask this question is, why can't a tubed tyre be made into tubeless?

The answer to your question is, because the tyre is not designed to carry an internal load larger than the weight of air. The sidewalls are not thick enough to cope with the added friction between the tube and the inner walls.

And because the tyre profile is totally different internally between a tubed and tubeless tyre. For a 155 section tyre the tubed version has a thickness of 5mm and the tubeless about 4mm (I may be a mm off, but a 20% difference is about right). The tubeless version would typically be made from a stiffer compound as well, to offset the reduction is wall thickness. They are completely different and are sold as two different part numbers by most manufacturers. 1mm does not sound like much but when a 400kg load is applied from above (1.6 ton loaded weight/4 tyres) along with engine torque - about 50 kg/m, you're talking spot forces greater than 2G. Excessive inner wear will rupture the tyre at worst, or cause uneven ride at best.

Using as spare is not an issue though. I still wouldn't have a tyre with a hole in it as a spare, but whatever works for you.