Correct width tyre and tramlining...?

[chrisgixer]

An oddity I am trying to understand.

 

I have 18" 8j rims currently with

235 40 18 sports contact 3 Ao1 (Audi approved fitment) which tramline noticeably.

But almost accpetable at the moment as they are fairly new.

 

245 40 18 sports contact 3 Mo (Mercedes approved fitment) No tramlining at all and I do mean NO tram lining on the same wheels, car and set up.

 

This might seem odd, as the wider 245 tyre tram lines less. But the standard fitment is 235 on a 17" rim. same width as the tramlining sc3 ao1.

So could it be that the narrower tyre means the sidewall angle is \__tread__/ shaped and the sidewall angle points away from the hub centre.

 

Where as the wider 245 allows a more verticle side wall |__tread__| and the sidewall angle is more towards the hub centre by comparison. Although we are only talking 10mm extra width. ...?

 

 

Or... Is there a construction difference within the ao1 tyre, that doesn't suit my omega? And the MO does?

Mercedes suspension design I thought was similar to omega, in a McPherson strut design. And that tyre does seem to work well.

Where as the Audi suspension design, as far as I'm aware, is more complex with multi links giving a double wishbone design, I believe? Firmer Audi suspension might allow a softer sidewall, making the ao1 less suitable for the omega.

 

 

Both tyre sizes are approved in the tuv certificate supplied by irmscher for the omega, who are the German 18" wheel manufacturer.

Any thoughts appreciated.

 

Chris

[Tony]

The 235 has a 94mm high sidewall and the 245 a 98mm sidewall, so the 235 wall is slightly stiffer and yes the sidewall on the 235 is perpendicular to the rim which is making matters worse. In addition there is a difference in the compound but this is more a wet weather grip thing.

[chrisgixer]

Thanks for quick reply.

 

Ok, so just to be sure, we are looking at this...

 

/___245___\ with higher sidewalls pointing at the hub centre on the MO. Which works.

 

|___235___| with relatively lower and hence stiffer side walls pointing away from the hub cente.

 

...effectively.

 

 

 

 

 

 

[chrisgixer]

Oh, and the side wall construction label is Differant too. I have pics somewhere. You may remember discussing this previously..?

How does the compound differ btw? Ao1 wearing quicker, if anything.

 

 

[Tony]

I'm not keen on this new EU labelling rubbish because each alphabetical addition is a measure of an undisclosed factor, lets say B performs three times worse than A?... So in essence the true measure is not as simple as A B C D and so on....... Most would read the difference that B is not quite as good as A, this is not the case.

 

I think the law in reduced tramlining is held within the tyres ability not to communicate road "irregularities" to the wheel, thus the driver. Distance and flexibility is the key, allowing the tyres sidewall to laterally deviate. A softer load rating and a high aspect ratio tyre is less communicative than a low profile run-flat tyre.