Info needed - Yokohama Tyres

No problems with mine on a Troopy, 38psi all round,

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Hi Kevin,

Clearly you are experiencing some problems and maybe you are unsure of the advice you've been given for the abnormalities you are experiencing. Without further information and preferably inspection, it is very hard to advise the causes of your issues. But from my tyre industry experience, can I offer the following for reference...

1. You should be running the tyre placarded pressure as that seems to be the OEM size for either vehicle you mention. But in any case on those vehicles on bitumen I would normally recommend 32-34psi all round unladen.

2. Tyres do not usually lose pressure although some are better at air retention over time. Inner liners do vary from brand to brand. Yokohama from tests I've seen have quality inner liners and should not normally lose air. Have the beads been tested for air loss, valve or valve stems and finally rims frequently fail or develop small cracks or may be porous?

3. By edge feathering, I am assuming you mean heal and toe wear, ie. each outer tread block is wearing unevenly with a scalloped effect. This is not the fault of the tyre but can be a natural affect of changes in steering geometry under braking and cornering and also it is normal for all steering alignment to have some toe-in which reduces vagueness at centre and improves "feel". Heavily lugged tyres like mud tyres and some all terrain tyres will be more susceptible to this than less agressive ones, but it is important that all tyres are cross rotated during their service to minimise this effect. In theory, this will happen with all tyres.

4. Correctly inflated and aligned tyres should all wear equally across the tread face. The crown radius, ie, the curve from tread shoulder to shoulder should remain consistent through the tread life of the tyre and tread depths be consistent when measured across the tread face (excepting across tie-bars and treadwear indicators). The crown radius should follow the curve of the case. If it does not, the usual suspect is misalignment. Bear also in mind that steering joints, bushes, shock absorbers and other components wear and some "play" is introduced as the wear increases. Few owners do it but the only solution is to fully replace worn components every 80,000-100,000 kms at most. Alignment can be "in specification" but still not prevent mal-wear on tyres.

From the tone of your post, I am speculating that your tyres are not proving satisfactory, but the very questions you ask lead me to believe that your tyres are unlikely to be the problem. Should you wish to enlighten me further, please post a little more info or perhaps we can find a way to communicate in private.

Regards,
John

I wouldn't put Yokohama tyres on a billy cart, I put them on a Toyota once, never again.

Cheers Steve.

John,

Now that I have had some very informative responses to my query - I put this on other forums as well - the story is:

LC came with Dunlop Grand Treks. 41000 kms they were shot so went back to Yokohamas because I had previous experience with the old pattern Geolanders. The wheels were balanced and aligned and I have some confidence in this dealer to do a good alignment. This is a new tread pattern tyre and after 3500kms of bitumn running with no towing I am happy with the ride and handling BUT

While the dealer set them at 36psi I have been having trouble keeping them at that. About every third/fourth day I was finding that they are down to 34, 32psi or a little less. At first I was blameing the weather since it was getting colder at night and I always check first up in the morning. Tubbing showed no signs of leakage on any of the four even though all four seemed to be dropping but not consistent. Initially blamed the guages as well.

Now after only 3500 kms of relatively easy running the edges on all four are showing quite severe heel and toe so I went back to the dealer who was concerned since this was his second similar situation within the week and fourth with similar symtoms in recent weeks. He has had the Yokohama rep on site to look at the other vehicles and has undertaken to have mine looked at in two weeks time when I return from a short trip. In the meantime I have increased pressure to 40psi and will maintain accurate record of performance over the next fortnight.

I am making no comments about Yokohama or the dealer nor what might be the cause of the 'fault'. Rather obvious that the end result is that the underinflation is causing the wear but more important to all is what is causing the pressure to drop.

Thank you for your response.

Kevin J