Hello Everyone, i have a few questions about my car, so basically i went from 16 inch wheels to 18 inch vrs wheels and now my car doesnt feel the same on the motorway when travelling 60mph+ its starting to swerve from left to right and opposite as if the car was jumping and is unstable on the road surface otherwise when driving slower the car feels stable and normal. The new wheels are all good have been balanced and checked out and all are okay. Today i have been for a 4 wheel allignment and that has been done but still the issue persists. Could it be suspension parts failing? Which parts should i look out for? Thank you.

A quick check for you; look at the tyre treads to see if there's any uneven wear, plus check for the correct tyre pressures and enough tread depth..

Tyre pressures are okay also tread is on all 4 tyres 5mm+ but only 1 tyre on front left has uneven wear basically there is more tread on the right side of the tyre than on the left but could that be the issue?

19 minutes ago, radas35 said:

only 1 tyre on front left has uneven wear basically there is more tread on the right side of the tyre than on the left

That suggests your tracking is out, perhaps adjustment, perhaps wear on the various suspension elements. Were it mine, I would get the tracking checked.

I had the tracking done today on all 4 wheels and is set at the correct figures and the issue still persists. So perhaps its the suspension parts which i was thinking but which parts specifically i do not know.

I had a Fiesta Mk3 which, after randomly spinning a 180 on a dual carriageway sliproad in dry conditions at no excessive speed I realised that I could change lanes with the throttle. Accelerate and the car would drift right, take my foot off the throttle a little and the car would drift left.

Ended up being a diff bush in a lower arm. Can’t remember whether it was the middle bush or the rear one. Would have remembered if it was bottom ball joint so it wasn’t that one. Might be with a look jacking that front nearside up and seeing if there is excessive movement.

More wear on the outside seems to suggests positive camber.

Not an expert but is the rolling radius the same from old to new wheels, plus the offset how much they stick in or out of arches, maybe upset the handling?

I guess it is going to be something to do with the lower arm i will have to get that checked out. Also the offset is the same and the wheels are not sticking out as i went to stock vrs wheels which are suitable for the octavia no aftermarket wheels.

One other quick check; swap the front wheels over and see if the driving behaviour follows the wheel or stays as-was.

@radas35 Is it used tyres that are now on the car? (Already shaped / misshaped) by the previous user) .What width and profile were the 16" and what are the 18"?, what brand / name tyres have you on now, and what pressure are they at?

Edited 8 March8 Mar by Evolution13

Yeah they are used tyres but are relatively new but only 1 tyre had slightly uneven wear on the front. The width and profile on the 16" was 205/55/16 and now i have 225/40/18. On the front i have speedarrows (halfords own brand) and on the rear i have uniroyals rainsport. The rear i have at 34psi and the front at 36 psi.

I would as suggested by @MikeTheThinker swap front to back. Behaviour is likely to just crap tyres. 'Arrowspeed'.Not Halfords own brand, Kwik Fit sell them. Check the manufacturing dates.

Edited 8 March8 Mar by Evolution13

15 hours ago, radas35 said:

Tyre pressures are okay also tread is on all 4 tyres 5mm+ but only 1 tyre on front left has uneven wear basically there is more tread on the right side of the tyre than on the left but could that be the issue?

You say the pressures are "OK" but what pressures are you running? Ignore, I see already answered.

IMO, you have the pressures back to front - rear pressures should normally be same or higher than fronts.

Edited 8 March8 Mar by Warrior193
correction

1 hour ago, radas35 said:

Yeah they are used tyres but are relatively new but only 1 tyre had slightly uneven wear on the front. The width and profile on the 16" was 205/55/16 and now i have 225/40/18. On the front i have speedarrows (halfords own brand) and on the rear i have uniroyals rainsport. The rear i have at 34psi and the front at 36 psi.

See my other comment - I believe you have front/rear pressure bias wrong.

225/45/18 are a wider tyre so may tend to follow road deffects more. I used to run same size on a people carrier and had found that I needed more pressure on the low profile tyres than the standard ones. It could also be the make of tyre.

Alasdair

5 hours ago, Evolution13 said:

I would as suggested by @MikeTheThinker swap front to back. Behaviour is likely to just crap tyres. 'Arrowspeed'.Not Halfords own brand, Kwik Fit sell them. Check the manufacturing dates.

Checked the manufacturing dates and they are only 2 years old 13/24 is the DOT

4 hours ago, Warrior193 said:

See my other comment - I believe you have front/rear pressure bias wrong.

I will try to change the tyre pressures and see if the problem persists

4 hours ago, Alasdair1 said:

225/45/18 are a wider tyre so may tend to follow road deffects more. I used to run same size on a people carrier and had found that I needed more pressure on the low profile tyres than the standard ones. It could also be the make of tyre.

Alasdair

The tyres is have are 225/40/18 so lower profile but have 34-36 psi and the rear tyres are uniroyals and the front are arrowspeed

Maybe the arrow speed tires. Try and swap front to rear and see if the uniroyals are any better. Arrowspeed I think is a budget/mid range. Had autogrip budget tyres/same size on my people carrier and they used to do the same.

Alasdair

Check to make sure directional tyres fitted correctly also

1 hour ago, Alasdair1 said:

Maybe the arrow speed tires. Try and swap front to rear and see if the uniroyals are any better. Arrowspeed I think is a budget/mid range. Had autogrip budget tyres/same size on my people carrier and they used to do the same.

Alasdair

Will try that and see if that is the issue

38 minutes ago, gav_is_con said:

Check to make sure directional tyres fitted correctly also

They are fitted correctly

In your original post you said the vehicle 'swerves' to left - do you mean it is a sudden, uncontrollable move - or is it a more gradual movement to the left when the steering wheel is released?

When i hold the steering wheel and the car swerves and feels like loosing control or traction and when i release the steering wheel the car still does the same