If you are buying used tyres, examine them very carefully for signs of deterioration. Don't just look at the depth of tread.

When I bought my efi TP sedan at the end of September, it was advertised as having "good tyres all round". I knew that would only mean its tyres had some tread left on them. In fact there were two different brands of Chinese tyres on the front, two Bridgestone radials on the back and an unused Bridgestone as the spare. At least they were all the same size and did have plenty of tread.

This car had a harsher ride than my carby TP, so I swapped all four shock absorbers and springs from the carby sedan as described in an earlier thread. That only made a slight difference. It still felt harsh. Chinese tyres have a reputation for hardness, so I removed those temporarily and substituted two Michelins at the front from the carby sedan. Again there was only a slight improvement.

On last week's trip to Tamworth, it seemed to be getting worse. At very low speed, it felt as if there was a buckled wheel. At 100 kph, it would make your teeth rattle. I couldn't see anything wrong from a visual inspection but was thinking perhaps a bent drive shaft or bad cv joint. Then I thought "maybe it's the rear tyres". Just as the thought crossed my mind, there was a thump at the rear and something flew off the back. The car lurched right but only went slightly sideways. I was on a gentle curve at the time at about 95 kph and brought it to a stop after a couple of hundred metres with lots of scraping and thumping noises. I thought the rear axle must have come adrift but when I got out I could see the right rear tyre had disintegrated and it was running on the rim.

I put the spare wheel on and drove slowly the rest of the way home. The ride was still harsh, so I suspected the left rear was also about to go. That was confirmed when I took it off later.

In this picture of it, the tread on left of centre is higher than on the right and it is starting to come apart. It varies dramatically around the circumference with the right side being higher in some places. This is not obvious at all when on the car with the weight on it.

http://users.tpg.com.au/acheson1/images/Tyre2_Distortion.jpg

My first thought was that although I had checked, I must have missed that they were re-treads. In fact, they are not. It seems to be just deterioration due to age but not easy to pick as the sidewall looks fine (scuffing is due to running on the rim). These pics are of the blown tyre:

http://users.tpg.com.au/acheson1/images/Sidewall.jpg
http://users.tpg.com.au/acheson1/images/Tyre1.jpg
http://users.tpg.com.au/acheson1/images/Tyre1_Pic2.jpg
http://users.tpg.com.au/acheson1/images/Tyre1_Pic3.jpg

I've now swapped the best of the Michelins from the wagon and carby sedan, so have Michelins all round including the spare. The smooth ride has returned.

Whoah!

Can you tell us the age of tyres, using the info from here (http://www.bridgestone.com.au/tyres/passenger/care/age.aspx)

That's good information. I wasn't aware of it and most people wouldn't be unless in the industry. The blown tyre and the one that was on the left rear both had the same three digits: 488

http://users.tpg.com.au/acheson1/images/TyreCode.jpg

The mark after the code doesn't look like a triangle so that would make it 1988 which is surprising since it is a 1990 model TP.

The tyre that was the spare also has only three digits: 460. Can't get a photo at the moment but the mark after it looks like a circle rather than a triangle, so unsure whether that means 1990 or 2000. It certainly seems very much newer but I'm not going to trust it anyway.

Thank you very much for posting that link. I will bookmark it for future reference.

Its been discussed here before somewhere in mass of threads we have, about tyre age, and tyres up to five years old, may still be reliable, but after 8 years or so, must of the binding strength has been lost, and not something I would drive on, especially over 80 kmph..

That was a very lucky escape....glad there was no other damage. How is the engine running now?

Yes, I was glad I hadn't switched those tyres to the front as originally intended. That might have been harder to control. The engine is running well. There are no oil leaks and it doesn't use or lose coolant at all. It runs smooth and starts instantly, doesn't smoke or use oil. Power on hills seems a bit weak but it goes well through the gears. The car passed its roadworthy so is now registered for another 12 months.

I've been thinking about the age of the tyres and it doesn't make much sense. The car had 61,460 kms on it when I bought it, so they can't be the original tyres. They must be at least the second set. At that rate of usage, they wouldn't have needed replacement for quite a few years, so how come they are dated 1988. He must have swapped them from an older car or bought them used. Anyway, it's all history now but i will be more careful in future.

I must admit I only had a quick read of the date code reference,its really informative,but is it possible they are 1998 ? As I said,I didn't have a chance to really nut it out,but 98 would make a tad more sense?

Yes, that would make sense but the date code is supposed to be followed by a triangle symbol if in the 1990s. There was no triangle in the 1980s.

Ah yes,the old triangle,missed that bit...mind you,the example they show is 1995 and it doesn't seem to have a triangle either....who knows,but one thing for sure ,those tyres are buggered. As you say,if it was on the front it may have been very interesting. I bought a set of new tyres from a used tyre guy recently so went out and checked,the fronts are pirellis made in 2013, the rears are Dunlops,2007. They were brand new old stock,no cracking etc,they look new,but will keep an eye on them.
Its good to hear your engine is behaving,bit weak up hills but ok through the gears sounds like a standard Magna engine to me! Cheers

Thanks for the info, I recently got some used tires and had a bit of a vibration in the front, thought it may just be one of em is unbalanced, switched the one with a tire from the back and seems to be better, but may just pop em off and have a good look at them to see if they look anything like the picture you posted. cheers

Hy there, a relative had a lend of my TP Elante, he thought front tyres were a bit flat so he put 60 psi in one tyre and 45 in the other side, after I got back I noticed a thumping noise and vibration, the 45 tyre recoved not the 60

hope relative replaced tyre


oh ok just read your last post

your tyres lasted 17 years ..must have looked after them

Hello magna buff, no, I didn't tell him about, the tyres were nearly 17 yrs old and the car is now scrap

Rather a coincidence that I came across this thread today, as earlier this morning I was told that my other car, a Wolseley 15/60, would not pass its registration inspection unless I had four new tyres fitted, as the sidewalls on the existing tyres were beginning to crack.

As well as owning a Wolseley, I am also on the committee of the Wolseley Car Club of NSW, being the editor of the club's monthly magazine. I had a feeling I had seen something on this before and, looking through my back copies of the club's magazine, I found back in 2008, a brief article (reprinted from Wolseley World, the bi-monthly magazine of the English organisation, the Wolseley Register), which read as follows:

Car tyres are made from a synthetic butadiene rubber which is easy to manufacture nad has a significantly loer cost than natural rubber, but it does have the disadvantage that it is more prone to oxidisation. To counter this, tyre compounds contain anti-aging additives as well as "extender oils" that improve grip and elasticity. Unfortunately, the chemicals that provide these properties are themselves harmful to human health and the amounts that may be used are strictly controlled at a level that provides a compromise between the need for tyres to last a reasonable time and the requirement to minimise the health risk. The "reasonable time" is around ten years, which in the context of tyres for vehicles that are in regular use is more than adequate. The oxidisation means that the character of the compound is deteriorating from day one, but the effect is barely perceptible in the first few years if the tyre is looked after or stored properly.

If a tyre has been in regular use beyond that period there should not be a problem provided the tyre is kept at the correct pressure (to avoid risk of overheating). But if the tyre has been standing for months on end, the oxidisation of the compound means a stiffening of the tyre walls so that when it is next used, the unaccustomed flexing will cause heat to build up more rapidly than it would in a newer tyre or one that was used regularly. When the tyre warms to a critical level, the natural degradation of the compound increases rapidly causing the long molecular chains that give the compound its flexible properties to shorten, and ultimately to cause the tyre to start to break up.

If you Google "tyre degradation" you will find that there is quite a bit of information out there about the subject. here is one that offers a pretty good overview of all the aspects of it: http://www.theaa.com/motoring_advice/safety/tyre-life-and-age.html

Footnote to the above: the tyres on the Wolseley were manufactured in 2001.

Footnote to the above: the tyres on the Wolseley were manufactured in 2001.

I had to replace them when it went in for its rego check a few months ago. There was still plenty of tread left but there were cracks in the walls. Fortunately the Wolseley uses tyres are pretty cheap - same as those on a VW Beetle.

I had to replace them when it went in for its rego check a few months ago. There was still plenty of tread left but there were cracks in the walls. Fortunately the Wolseley uses tyres are pretty cheap - same as those on a VW Beetle.

I've now checked the dates of all tyres that were on the car in the original post at time of purchase. The two Chinese tyres on the front were 2008 and March 2012. Presumably the 2012 one should still be ok. The two Bridgestones on the back were either 1988 or 1998 depending on interpretation of the codes. Either way, far too old. Ditto for the unused Bridgestone spare which was either 1990 or 2000. Also just noticed that, contrary to my original post, the Chinese tyres are 185 70 R14 while the bridgestones are 175 75 R14.

The Michelins on it now were ones I purchased myself. I bought a full set when I got my TP wagon and another full set when I bought the carby TP sedan. They are also getting too old now but in any case there's not much tread left, so I will be buying another set of Michelins in the next two months. 185 70 R14 is the closest Michelin size now available to the original Mitsubishi spec. of 175 75 R14. They are $160 each, so I will buy a pair at a time. I'm tossing up whether to use the 2012 Chinese tyre as the spare since it is the same size and will probably never be used.

The reason for the Michelin fetish is that the TM Magna I bought in 1987 did not have power steering. It came from the factory with Dunlop SP's which were horrible in every way. I had them replaced with Michelins and could feel the difference just driving it off the showroom floor - much less steering effort and much less road noise. They last well too. I get about 50,000 kms. They're also good for cornering in the wet, not so good for braking.