Beware of over-inflating old tires!

[kingsway]

The date of manufacture is a 4 digit number on the side-wall comprising week and year - eg '3605' would be week '36' of year '05'


Here's the tyre in question...

For some reason you can't really see the bulging/distortion, but you can see the cracks in the rubber at the centre of the bulge area (right side of treads)



The car has just passed its annual inspection (MOT) and did have an 'advisory' which mentioned 'slight cracking' in this tyre. I thought they meant the slight crazing in the sidewalls - had I had any idea it was as bad as it is, I would have done something about it immediately!

Maybe it was the higher pressure that high-lighted the problem?

No harm done, luckily, but running old tyres could have proved to be a very false economy!


BTW running at 30psi instead of 40psi (4 psi below max) appeared to make a difference of 2-3mpg at steady speeds according to a quick and dirty test using my Ultraguage!

[Frank Lee]

Five year tire life is just as nonsensical as the 3000 mile oil change and parts-store recs on replacing spark plug wires. I've had my '59 for 12 years (I think) and I put the wide whites on there... purchased used so who even knows how old they are (should look for the code). I run 'em all until either the cords stick out or they blow. Never had a tire incident I can describe as scary. Extract the last mile outta them before they end up in the landfill.

^That herniated tire probably just has cord separation; I've had that happen too... don't know if it's a direct result of "over"inflation... I suspect age/mfg defects/a severe impact at some point play a part in it too. I will replace a tire with that too- they're simply too lumpy to ride on and it'll only get worse.

[kingsway]

I read a recent report where tests had shown that stopping distances with tyres at the UK legal mininum tread-depth of 1.6 mm were twice as long as those of an identical tyre/car with 3mm of tread... So that small difference - even with a tyre that is not time-expired (very hard rubber) - could make the difference between having a collision and avoiding one....


I'm a Driving Instructor so regularly have people practicing 'emergency stops' in my cars - usually at 20mph or so.

My little automatic which also had its original 2003 tyres on it, would lock-up all four wheels and skid very nicely - even in the dry ! A set of new Michelins all round has made a world of difference...

It all depends on how you drive and the area you drive in. For me, life is short enough as it is. I also drive in a place where roads are very narrow, winding and congested.

The novices (my pupils) are seldom a problem, but there are plenty of so-called full-licence-holders in other vehicles who scare the hell out of me on a daily basis! I need all the braking-effort and traction I can get!

[Frank Lee]

Sounds like you live close to the edge. I could probably pinch off the lines to the brakes on three of my wheels and get by pretty good with just the one brake, because I'm on them so lightly and sparingly. My '94 F150 is still wearing the factory pads and shoes and drums and rotors; I've had to replace some of the hard brake lines due to road salt rust though. I just replaced the pads and shoes for the first time on the '92 Tempo I've had 12 years not because they were worn out, but because the linings were delaminating from the backings! If they would have been rivted + bonded construction instead of just bonded I probably wouldn't have had to replace them.

[Ryland]

They are a 65,000 mile tire that you have 67,000 miles on, so I'd be pretty happy right there.
I also wouldn't feel safe ridding in a vehicle that only had 20psi in the tires, seeing as how most tire blow outs are caused by low pressure and the heat build up that happens because of to low of pressure.
Either way you make a good point that when tires are reaching the end of their design life that it is a good idea to inspect them for damage.

[jamesqf]

Originally Posted by Frank Lee

^That herniated tire probably just has cord separation; I've had that happen too... don't know if it's a direct result of "over"inflation... I suspect age/mfg defects/a severe impact at some point play a part in it too.

Yeah. I'd think that inflation pressure has nothing to do with this. More important, once it has happened, backing off the pressure will do nothing to make that tire safe to drive on, and will probably make it worse.

[Fat Charlie]

Originally Posted by Ryland

They are a 65,000 mile tire that you have 67,000 miles on, so I'd be pretty happy right there.

I'm never happy with a part that's only got a lifespan 3% longer than the warranty. Yes, tires are a wear item and pro-rated warranties are really nothing more than a sales tool a sales tool, but it still wouldn't make me happy.

[roflwaffle]

I'd only expect the rated mileage if you drive according to the test that does the rating. IE only going 55mph on a perfect track in the spring. Anything else will induce greater wear.

[redpoint5]

5 years is maximum tire life! Sounds like something a tire salesman would say...

My dad gave me his '76 CB750 motorcycle with original tires and I rode it until the tread was worn out.

Recently I found a gouge on one of my car tires sidewall. I rotated that tire to the back just in case it blows out, but I don't expect that will happen.

As others have said, running 40psi didn't cause the bulge. Likely a manufacturing defect or something the tire ran over caused damage. If it were me, I'd move the tire to the rear, air them back up to 40psi, and run them down to the minimum tread you can tolerate.

[euromodder]

Originally Posted by Frank Lee

I run 'em all until either the cords stick out or they blow.

Pretty irresponsible IMHO.

We have a 1.6mm legal limit and annual car inspections in Europe.
They won't let you pass with shot tyres.