Mixing Tyres/Poor Handling

[Ed Doe]

I disagree that all our cars are different.

I would certainly get the alignment checked if it hasn't been done for some time.

Bear in mind that if you're running standard camber you'll have worn the rear inside of the main belt more than the outside - your old tyres would therefore have a greater effective contact patch perpendicular to the road. Your new tyres by comparison won't be worn so you'll be running marginally more on the inner edge - making it feel more like it tramlines at the moment.

At the end of the day it can only be worn bushes, alignment or tyre pressures. Which is the same combination as with any other zed (electric steering on the si's notwithstanding).

If the tyres are fresh on I'd get some dry seat time, do a tank of fuel getting them properly scrubbed in and take it from there, but alignment would be the next thing on the list if it were me.

[flimper]

An interesting post on Pistonheads about it, definitely need to get the Supersports off ASAP, the handling is horrible

[MrPT]

That doesn’t make much sense to me. Also... “twitch” at the front and “flop” at the rear, rounded off with an appraisal of how well they lay down chav tracks?!

Mismatched sidewall profile front-to-rear (and hence, mismatched sidewall stiffness) is a feature of a lot of cars famous for their handling - 600LT, GT3 RS, Ferrari 488, AMG GT-R etc.

I’d experiment with pressures first.

[MACK]

Mine has been unpleasant since I bought it. I fixed three issues relating to the steering and handling on the front end, as well as having a four wheel alignment, but the front was still nervous on all road types (particularly with changing camber).

I fitted new Toyo Proxes on the rear a few weeks ago but swapped them to the front out of interest...totally different car. The fronts and rears have never been matched on my Z4 in my 10 months of ownership, and they still aren't, but the front tyres were ruining the steering. They had worn with a raised band roughly in the middle of the tread, about 5 mm wide and 1 mm tall, and this band wandered from side to side across the face a little as you rotated the wheel. None of the tyres have been run flats, and all premium brands, but this was my final issue.

Interesting. My PS3's on the front that I binned despite having a good 5mm of tread left had very similar strange wear. The tyres were the source of the tramlining and other issues. I've refreshed everything on the front end and the alignment was fine so I knew in the end it could only be the tyres. I even tried backing the the camber off from maxed out to stock before going to the expense of changing the tyres. I put the strange wear down to the fact that the front end needed a complete overhaul before I did it and the alignment was out from before I got it. I only actually noticed the strange wear once the tyres were off the car and under close inspection.

[wonkydonkey]

MACK I'm sure you were kicking yourself as hard as I was when I finally changed the easiest (and arguably most obvious) factor that can affectt steering. I'm also sure you're similarly happy to have a car that holds its line now!

[MACK]

MACK I'm sure you were kicking yourself as hard as I was when I finally changed the easiest (and arguably most obvious) factor that can affectt steering. I'm also sure you're similarly happy to have a car that holds its line now!

Sure was and sure am!
I can laugh about it now...........just!!!

[andyf1140]

When I bought mine it had budget tyres all round and handled fine. I changed the rears for Avons and it was positively dangerous. Now I have put Avons on the front as well it's spot on again....

[road warrior]

Two things have become clear since running my Z4 and hanging around the forums, these cars are unusually sensitive to changes in tyres/pressures, suspension/bushes, alignment and wear of course.
2nd, sorting it out based on others experience is hit-and-miss. Few cars are alike now, what with swapping from RFT's, wheel size changes, non-OEM springs and bushes, alignment changes and wear, then it's always proven difficult to do anything other than work through the list of possibles.
It took me ages! Replacing a broken rear spring, saggy bushes, new non-RFT tyres, a Hunter 4-wheel alignment and tyre pressures got rid of 80% of the problem, it took 2 alignments with someone who knew what they were doing and was able to take account of changes (rather than sticking to the computer's specs) to finally sort it.

Your absolutely spot on and I agree, nobody has the same setup or wheels or tyres or amount of wear or even tyre pressures so impossible to say, I do feel that tyres need to bed in before adjusting anything, that said our stupid electric steering is bloody awful and when I do get rid of my z4 it will be for that reason.

[Jembo]

Two things have become clear since running my Z4 and hanging around the forums, these cars are unusually sensitive to changes in tyres/pressures, suspension/bushes, alignment and wear of course.
2nd, sorting it out based on others experience is hit-and-miss. Few cars are alike now, what with swapping from RFT's, wheel size changes, non-OEM springs and bushes, alignment changes and wear, then it's always proven difficult to do anything other than work through the list of possibles.
It took me ages! Replacing a broken rear spring, saggy bushes, new non-RFT tyres, a Hunter 4-wheel alignment and tyre pressures got rid of 80% of the problem, it took 2 alignments with someone who knew what they were doing and was able to take account of changes (rather than sticking to the computer's specs) to finally sort it.

Your absolutely spot on and I agree, nobody has the same setup or wheels or tyres or amount of wear or even tyre pressures so impossible to say, I do feel that tyres need to bed in before adjusting anything, that said our stupid electric steering is bloody awful and when I do get rid of my z4 it will be for that reason.

Worth trying the steering in a M, significantly different