I have recently swapped in my 06 Octy II vRS TFSI hatch (wore standard 17" alloys) for an ex-demo VW Passat CC GT wearing factory 18" alloys (235/40's). The new car (140 CR diesel) is great - only problem I have is it doesn't steer straight. If I hold the steering wheel dead ahead on a straight piece of raod, the car veers into the nearside verge (not fiercely, but it's definately there).

My question is, is this likley to be a wheel allignment issue or is it possible that it is just the 18" alloys following the camber of the road (ie the classic 'they all do that, Sir' ).

Do any of you with 18's on your vRS experience the same thing? (My vRS wearing 17's always steered straight as a dye)

Thanks

vRS Fred

No, I didn't. My vRS and 18" steer fine.

Some tyres "tramline" terribly and it can also depend on how worn they are. I used to run a car with 195/45/14's instead of the standard 165/55/13 and it was hilarious - you had to avoid the inside lane on the motorway!!

Tyres with low proliles develop lots of cornering power at lower slip angles than "standard" aspect ratios and will therefore generally be more susceptible to tramlining than standard tyres that develop less cornering force until their slip angle increases. It also goes without saying that the wider the tyre, the more chance of it coming into contact with longitudinal ruts and therefore more chance of tramlining.

A contributing factor can be the amount of castor angle which will have a direct effect on the sterring sensitivity but I don't know enough about it to comment further

Personally I'd get the geometry checked anyway to be on the safe side. .

Indeed I thought of tweaking my wife's Jazz steering in order to help the steer realign, by adding some caster (incidentally, the caster adding is provided by the WALK). The more the caster the easier wheels will align.

its not the wheels mate, its either the alignement or stiff tyre walls causing tramlining

I have 18" and they track true.

I have the 18/235/40's on my passat, let go of the wheel and it keeps going in a lovely straight line, id say it was almost certainly your alignment.

Tried Pirellis, Conti and im currently only vredstein ultrac sessantas and they' ve all kept the car goin dead ahead

My Z4 is on 18 inch wheels and run flat tyres whith sports suspension and if the road is flat it goes staight. But if it is rutted it goes were it pleases and you have to realy fight against it some times on the motorway.

I've just changed to 225/45/R18s and the car tracks just the same as it did on 17s.

Depending on how recently you got it can't you take it back and have a moan about it? Also make sure there is no sign of the car taking a knock in a deep pothole or a kerb, ex demos can sometimes lead a hard life.

Swap the front wheels round and see if it veers in the opposite direction - it may be a dodgy tyre. I had this on a Citroen C3 a few years ago and they solved the problem by moving the front wheels to the back - gits.

D

What happens if you let go of the steering wheel when the car is going straight ahead does the car still veer off, or does it continue in a straight line?

If it continues in a straight line then the steering wheel was probably not set 100% in the correct position when the tracking was set.

My Octavia VRS on 18" wheels also does this when holding the steering wheel at what should be the straight ahead position, if I release my grip and let go it runs in a straight line, but with the steering wheel slightly off the central postition.

Don,t think its the wheels or tyres but get the wheel alignment done to be sure.

Also Passat CC really nice car

...wonderful line, IMHO.