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[feeutfo]

Just a note, I am concerned purely with tram lining. Just that one single feature, I hate it with a passion.

[feeutfo]

Actually, on re checking the pics, the best handling mo has 1 ply rayon, where the slightly worse handling o1 Audi variant has 2ply rayon in the sidewall.

[cem_devecioglu]

what size do you actually have fitted at the moment ?

I am almost one million % certain it's not to do with width. Eg.........................................................

Chris, fit 195 65 15 size and see how it doesnt tramline

[cem_devecioglu]

I think I've got some sort of answer - are you sure that the two fronts you've had are 245/45 x 18 and 235/40 x 18 ?

As you know, the Omega B suspension is designed around tyres with 11.8 inches hub height. so that means that the roll centre and ground-level offset will be correct as long as you maintain this dimension. Happy handling territory.

Your 245/45s are quite a long way from this - half an inch height-wise to be precise, which is as good as a mile in suspension terms. They are also almost five percent bigger in rolling radius, too - this will certainly increase your braking distances as it'll confuse the ABS.

My considered opinion would be that its very difficult to find a 235 tyre of the appropriate size which won't tramline. And that your inappropriate ( sorry Chris ) size mitigates the tramlining, possibly by extending the ground-level offset and thereby giving more self-correcting torque.

Don't forget that the Omega B front suspension is almost identical to Omega A - so the tyre that they had in mind when they designed it was a 165 x 14.

245/45 x 18 = 780 wrpm & 12.3 inch hub height
235/40 x 18 = 820 wrpm & 11.8 inch hub height

265/35 x 18 = 823 wrpm

Also, the less height (in mm) in the sidewall means a stiffer tyre

agreed.. when the tyre size gets bigger both horizontally and vertically, the friction force between tyre and the road is multiplied by those lengths simply (actual forces will be more complex depending of the angles of arms, struts, and other components) and this force reflected to the steering as tramlining..

[2woody]

Yes, I'm with you - I think its a difference in the tyre construction that causes one to be more susseptible to tramlining than another. That difference won't, however, be in the number of plies of material a versus material b - that's way too simplistic. I've seen this sort of thing from two supposedly identical tyres made on different days.

If you've caused the ABS a headache at the rear, it'll show up in more ABS activity at the front, especially with too big tyres on.

My tyre fouling was radial with the 245s on.

[feeutfo]

Yes, I'm with you - I think its a difference in the tyre construction that causes one to be more susseptible to tramlining than another. That difference won't, however, be in the number of plies of material a versus material b - that's way too simplistic. I've seen this sort of thing from two supposedly identical tyres made on different days.

So what differentiates the Audi and Merc variants?

If you've caused the ABS a headache at the rear, it'll show up in more ABS activity at the front, especially with too big tyres on.

TheBoy has the same wheel size, with 235 45 18 tyres fitted. Exact same sizes. On approaching the same roundabout with those yellow warning lines horizontally painted on the road, on the same lines into the roundabout hard on the brakes, mine with sc3 will trip the abs earlier. His absorbs the bumps better, even with four completely different tyres on each corner, runway, auto grip, diamond back and some cheng slime make I can't remember. Since replaced with sc5 all round.
 Only thing in the back of my mind is the difference in perception as a driver and passenger. Your more plugged in as a driver and feel the controls better driving mine, but as a passenger in his the mind panic sets in early as not connected so maybe he feels the brakes better. I can't believe I'm harder on brakes than he is though, his braking is ...impressive. Both in bravery and judgement.Edit to add, his is 8j all round though, mine are 8j front,9j rear

My tyre fouling was radial with the 245s on.

Ah, so catching the bottom of the spring cup? There was about 5mill clearance on mine. A member here has a 50 profile tyre on the same wheels. They don't fit, spring cup fouls.

[05omegav6]

My tuppence fwiw...

Standard 17" 7Jhave an offset of ET33, with a tyre size of 235/45/17.

My Irmscher Stilas, at 18" 8J have the same ET33 offset with a tyre size of 235/40/18.

My tyre of choice is/are Runway Enduro 916+ Z rated with a 97W load rating.

These are constructed: Sidewall Polyester x2.
                                           Tread Polyester x2, Steel x2, Nylon x1

And are available in 16", 17" and 18".

As long as they are available, I shall continue to buy and use them

For a considered and intelligent impression of them, Kevin has just had a pair fitted to his MV6, with favourable first impressions

[Kevin Wood]

Yes, I can confirm that there are no tramlining issues with Runway Enduros in 235/45/17 at £67 fitted each.

I'm quite impressed with them so far, considering the weather has been truly sh1te since they have been fitted. About the only thing I can't comment on is grip in fine, dry conditions.

TBH, now I've found a setup where my tyres wear evenly I only get annoying tramlining when they are well worn, say under about 3mm of tread, and even then only on poor road surfaces generally. Given that means the last month or two of the tyre's life it's not really a problem. Of course, one man's slight tramlining is another man's uncontrollable.

We have to be sure we're talking about the same thing.

[2woody]

So what differentiates the Audi and Merc variants?

want a list ? so there's rubber hardness, security of bonding, tread pattern, age of tyre, rubber additives - all of which have much more influence on a tyre's behaviour than the carcass construction.

If you've caused the ABS a headache at the rear, it'll show up in more ABS activity at the front, especially with too big tyres on.

TheBoy has the same wheel size, with 235 45 18 tyres fitted. Exact same sizes. On approaching the same roundabout with those yellow warning lines horizontally painted on the road, on the same lines into the roundabout hard on the brakes, mine with sc3 will trip the abs earlier. His absorbs the bumps better, even with four completely different tyres on each corner, runway, auto grip, diamond back and some cheng slime make I can't remember. Since replaced with sc5 all round.
 Only thing in the back of my mind is the difference in perception as a driver and passenger. Your more plugged in as a driver and feel the controls better driving mine, but as a passenger in his the mind panic sets in early as not connected so maybe he feels the brakes better. I can't believe I'm harder on brakes than he is though, his braking is ...impressive. Both in bravery and judgement.Edit to add, his is 8j all round though, mine are 8j front,9j rear

His tyres are way over-size, too, just not as extreme as yours. I am assuming that he has the same tyres all round. Your early ABS onset is caused by the difference in rotational speed between the front and rear wheels on your car.

[feeutfo]

2woody as said. WE HAVE THE SAME TYRE SIZES of 235 40 18.

(The 245 45 18 where the previous size that did NOT tramline.)

Both sizes have the abs issue. (if it is an issue)


Sorry. Just to be clear. Unless I'm missing something?

[2woody]

cool - ignore my last post then

[TheBoy]

2woody as said. WE HAVE THE SAME TYRE SIZES of 235 40 18.

(The 245 45 18 where the previous size that did NOT tramline.)

Both sizes have the abs issue. (if it is an issue)


Sorry. Just to be clear. Unless I'm missing something?

Is that true? Your rears are 265? Unless I've missed a post, if so, sorry.

2woody has a valid point about rolling radii affecting ABS - it has to detect the tiniest variance in rotational speed, under quite complex conditions.  If the rolling radii vary, it will push it (artificially) towards the calculated thresholds.

Every Omega (standard) I've driven hard, with the exception of TDs, have a tendency to understeer in fast bends - something I've managed to dial out of the MV6. I see that wider rears will only make that worse. IMHO only, of course.


As for my experience, my MV6 stops far quicker than the Elite.  The tyres play a key roll, but obviously the Elite has an additional set of issues at play.

An unfair comparison, given the cars issues, but I can not tell a grip difference between the Sunew/Diamondback/WonTomSoup tyres I had, and the SC5's on now, except less vibration as the wheels are now round. From a tramlining/instability view, the SC5s are awful, to the point Mrs TB wont drive it. After loosing the rear in moderately hard braking (admittedly with a fair amount of lock on), I don't want to either. Though, as said, the car has other long term issues.

[feeutfo]

Back on topic please.

Now, this team lining....


TheBoy, as said, the rears do not affect team lining, as they where fitted while both sizes where fitted to the front.

Abs is for another day. But I would add, removing the too big 245 45 18 fronts (that did not tramline) and fitting the matching to the rears diameter 235 45 18 (that do tramline) has made not one jot of difference to the abs.




It's annoying that I have removed the front tyres that are too big, and are supposed to tram line more due to being too big, in favour of a tyre that matches the diameter of the rear, and the straight line handling is worse, and the abs is unchanged.afaict.

You see my point? Obviously something other than size is at play. What is it?

I don't really buy 2woodys list of age, compound, etc. when it's only straight line handling we are talking about. (obviously these affect other areas, fair do's)

The first thing Tony at Wim did, when discussing the problem, and discounting pressures and set up, was to look at the construction badge on the side if the tyre. This is merely a continuation of that thought process. ...?

[feeutfo]

And yes, the rears are 9j, but the same diameter.

This was discussed earlier.

[TheBoy]

There will be construction differences between different sizes. Beyond what is on the sidewalls.