Fitting New Tyres - Vehicle now "Drifting"

[mikeecix]

Have just replaced front Michelin Primacy HPs with Kumho KU31 97W and rear Dunlops with Kumhos too.

After fitting, I noticed the car did not track in a straight line but "drifted" to the right on acceleration and to the left on deceleration. Previously with the Michelins, it never drifted and was completely true under acceleration and braking.

The drifting is most noticeable when on cruise control - with the power constantly adjusting to maintain the set speed, it will drift left or right depending if accelerating or decelerating. I can replicate this drift by manually adjusting the set speed up or down.

I originally thought the tyres needed some "bedding in" but after 2 weeks and 1,000 miles, it's no different.

I decided to have the vehicle wheel alignment checked - here are the results of the Hunter 4-wheel alignment check:



There has been no difference since the alignment was adjusted so I am returning to the garage to see what else can be done to resolve this issue. As you can see from above, the left-front camber was originally green but now red - they couldn't adjust any further to get it back within tolerance.

Does anyone else have any experience of changes to vehicle tracking after a tyre change? I'm wondering if the Kumho's just don't work well with my vehicle and I should switch back to the more expensive Michelins.

I opted for the Kumhos based upon various user reviews which were very positive - cost (£78 per corner), noise, rim protection all good. I agree that they are quieter but they have slighly less rim protection than the Michelins (have scraped one of my alloys since fitting) and I'm finding a drop in fuel economy of approx 3-4mpg. This reduced fuel economy in itself will cost me more in the long-term over the more expensive Michelins (£130 per corner) so I'm considering switching back just for this. However, the main issue is the drifting which is making driving far less pleasurable and more tiring.

Has anyone else has issues with tyre changes?
Should I get the rears swapped to the front to see if the drift is still present?
Would new tyres possibly be highlighting suspension wear which was previously "masked" by the old tyres?

My vehicle has covered 109,000 miles but is in pretty tip-top condition. The only issue from the previous MOT is an advisory regarding wear to the front suspension arm bushes (causing the dreaded creaking over speed-humps). Will probably need replacing in about 12 months.

Any advice would be most appreciated......

Cheers,

-Mikee-

[martin1810]

Wheel alignment is measured against wheels not tyres, so tyres have nothing to do with it. BUT when a tyre rests on the floor it strains the suspension and movement in the suspension could change the wheel alignment. The old tyres will have settled in to suit the suspension. The new tyres haven't, so may "stand" differently. The new tyres may wear in to match the old ones or they may not. No one can answer that one. If the answer to this was simple , formular one cars wouldn't suddenly change performance during a race, just because the tyres were changed.

[Quatrelle]

I've changed tyres on my cars over many years and never noticed that sort of difference.

Silly question perhaps, but assuming they're asymmetrical, have they been fitted the right way round?

[bigstuff]

Would new tyres possibly be highlighting suspension wear which was previously "masked" by the old tyres?


Cheers,

-Mikee-

Nail on the head in my opinion. Extra grip of new tyres pronoucing wear / movement.

[Quatrelle]

Nail on the head in my opinion. Extra grip of new tyres pronoucing wear / movement.

....and wouldn't that make accurate tracking difficult?

Is there any movement in the bottom wishbone arms?

[redrolo]

What was the wear like on your old tyres? This would explain if there is a suspension issue wouldnt it?

[bigstuff]

What was the wear like on your old tyres? This would explain if there is a suspension issue wouldnt it?

Possibly but not necessarily.

[redrolo]

Possibly but not necessarily.

It would as you would identify uneven wear from an individual tyre

[Tony_Essex]

Weirdly I have experienced a similar thing for the first time this week. I replaced the aging Dunlops with some Hankook tyres, and now my steering wheel is no longer straight! The good news is that the car does not pull in either direction, so I am not overly concerned, but I will get the alignment checked on Monday, as I would prefer a straight steering wheel. I had all four tyres changed, and notice that the wheels that were on the front are now on the back, and vice versa. But this shouldn't have any impact. I have never had this before and am tempted to only get two wheels changed at a time now.

Regarding fuel consumption, don't forget when you put new tyres on they are softer thatn the old tyres, which could be a few years old (and hence very hard). The old hard tyres don't grip as well and have a much lower rolling resistance.

Tony

[mikeecix]

What was the wear like on your old tyres? This would explain if there is a suspension issue wouldnt it?

The wear was pretty even across the tread of the old tyres.

Went back to the garage and had the front/rears swapped over. Certainly seems to have made a difference but it's still not perfect. Will see if things settle down over the next few thousand miles. I might actually get the bushes/wishbones replaced anyway as they were an advisory on the last MOT and the garage had a look and reckoned the nearside one has a fair amount of play in it.

-Mikee-