Help with tyres, tramlining & high-speed stability

P

pdk42

Member
 Leamington Spa
Hi all,

I've had my Zed (E85 3.0) a few weeks now and I've been pretty happy with it all told. There was some tramlining from the off, but nothing I thought was alarming and anyhow, the rears were down to 2mm or less so I thought that was probably part of it.

Anyhow, I had the alloys re-painted yesterday and also had two new rear tyres fitted (the original ones were down to about 2mm or less). The car had Falken 452s all round but I read some good reviews of the Nexen N8000 and found some at a good price on Tyreleader, so that's what I had fitted.

I took the car for a blast after all this and immediately noticed that the tramlining, especially at speed (60mph+), seems a lot worse. So much so, the car feels quite twitchy and not very re-assuring. It's definitely not as I remember it. I fiddled with tyre pressures a bit and put them all down to about 32PSI, which I think has improved things a bit, but maybe I'm now over-analysing things! Maybe I'm also just pushing it too hard. While I was waiting for the work to be done, I had a test drive in a Golf R and that's just such a sure-footed car maybe I'm being unrealistic?

So, I guess I could do with some guidance. I suspect the fact is that I've just bought crap tyres and I should cut my losses and go get some Falkens! But, maybe I should give them a bit of time to bed in, and maybe I need to play with the pressures a bit - I hear that the Zed can be very sensitive to that.

Thoughts?
 
I doubt its the rear tyres that is producing the twitchy ride & if you were closer i would happily lend you some different wheels/tyres to try out.
The topic comes up so many times & is a pita for the owner when there is that little niggle or unnerving twitch at certain speeds & surfaces :( Trial & error can be a solution , i certainly wouldn't throw a set of new Falken's on in the hope that will cure it :?
I'm currently on Conti rears / Michelin fronts & it is 100% sweet & steady at any speed ,any surface but i have had temporary sets on the same car & it drove completely different :wink:
 
Thanks for the helpful words. If things don't bed in, I can see me paying a visit to Pendle to take Mr Wilks up on his offer (ironic, I bought the car from Clitheroe!). It's interesting that the Zed is so sensitive to the rubber it has fitted.
 
pdk42 said:
Thanks for the helpful words. If things don't bed in, I can see me paying a visit to Pendle to take Mr Wilks up on his offer (ironic, I bought the car from Clitheroe!). It's interesting that the Zed is so sensitive to the rubber it has fitted.
Click to expand...

Come on back mate , i'm only about 8miles from Clitheroe & have a few sets of different size wheels/different tyres you can try out ,
i stuck a set of perfectly balanced 19inch style 296s with 5-6mm Pirellis on for a few days :roll: it wasn't totally bad but it wasn't as it is now , 75/85 you could feel a light twitch on the wheel that made me uneasy to the point i wanted to slow off which doesn't instill driver enjoyment or confidence .
 
Thanks so much for your help on this! What pressures do you normally run your tyres at? The manual says 2.3 bar front, 2.6 rear (33/37psi) but the previous owner said he ran them lower (but I didn't check the pressure before the wheel refurb and new tyres).
 
32-33 front / 34-36 rear works for me but folks like to do their own numbers :wink: it can be trial & error with different tyre makes .
Some Falken tyres have been known to look "tight" on the rim whereas others can look opposite ?
I should also mention i upsized my tyres to the M spec profiles of 45 front & 40 rear which i can recommend for comfort & also closes arch gap without need to change the springs :wink:
 
That's a nice idea about up-sizing the tyres. The thought had crossed my mind in fact to improve the ride a little. I guess it causes some under-reading on the speedo?
 
pdk42 said:
That's a nice idea about up-sizing the tyres. The thought had crossed my mind in fact to improve the ride a little. I guess it causes some under-reading on the speedo?
Click to expand...

Indeed , -2% against the factory staggered 18inch set up so nothing of concern but yes the ride quality improves i would say :wink:
 
Hi pdk42, Can't stress how useful a 4 wheel alignment would be also. Go to somewhere that uses a Hunter or similar machine. It will cost you anything from £40 - £120 depending on how much is adjusted but will given you a far nicer ride at speed. Now that you have fresh tyres also so previous 2mm and now 8mm this will impact the tracking alignment...so best to get it adjust back to factory spec.... :thumbsup:
 
How many miles have you got on the new tyres? I would give them a few hundred miles before making your mind up - get them well scrubbed in. I dropped my rear tyres to 32 and it helped to settle handling but as has been said it is an individual thing.

Don't be put off though because improvements can be made.

:driving: :thumbsup:
 
I thought I'd give an update on this... I've held back from doing tyre swaps since the consensus seems to be that rear tyres shouldn't make a huge difference. So, I thought the best thing was to get the alignment checked. The toe in on the nearside front was slightly out, but it was pretty minor. I got it corrected anyhow but it made no difference. Everything else was in good shape. The steering bushes etc are all in good condition.

So I started paying more attention to the issue. The car handles fine when cornering, even on uneven surfaces - but it tramlines in the straight-ahead position and it gets a lot worse with speed. I also noticed that on fast-ish right bends, but well below the point of loss of traction, the DTC/DSC light would flash. The same doesn't seem to happen on left bends. So, I started to think maybe it's power-steering related. So, having read about steering angle sensor issues, I did a full left/full right sweep of the steering at rest and somewhat to my surprise the car is behaving a lot better!

I'm wondering if I should get the sensor replaced, but I'd like to get it checked first. I recall seeing a YouTube video of someone using a handheld diagnostic box, probably plugged into the OBD, which showed the steering angle returns from the sensor. Do any of you guys know what that might be? Would a BMW dealer or Indy have such a thing?

Anyhow, having read a bit about steering issues with the Z4, it does seem these sort of problems are not uncommon. I believe there was even a recall in the USA for similar problems.
 
An inexpensive OBD cable with INPA diagnostic software from Ebay can show the steering angle, as well as lots of other diagnostic information.
 
You must log in or register to reply here.
Back
Top Bottom