Hi all,

Hopefully one of you most knowledgeable folks can help me.

I own a 2001 GS430 Sport (basically one of a limited number of GS430 SE's with the sport styling kit). The car came fitted with 4 x Dunlop SP Sport 9000 245/40/ZR18. The tyres all have good tread and are relatively new but I've noted that the offside rear tyre has two puncture repairs.

Anyway I have handling problems when the road is uneven or rough - unfortunately this is the case with a lot of the roads in my area. Basically the steering twitches like a bucking bronco, and needs constant minor adjustment. If you come to a stop on a sloping road the steering turns gradually in the direction of the slope. The car handles quite well on flat roads and there is no steering "pull" when braking except of course if the road happens to be uneven at the time

I did take the car in to my Lexus main dealer, and they checked the suspension and shocks (all OK - phew!) and did a 4 wheel alignment (over £100 quid - ouch!). Though the geometry was slightly out, the alignment has has not cured the problem

Now I understand from reading the board and Googling that the symptoms I've described are the classic symptoms of tramlining, and tyre pressures could be the problem. The tyres on my GS430 are all set to 32 psi. The owner manual has a printed sticker in the tyre pressures section which states a recommended pressure of 32 psi front & rear for up to 4 people for speeds of up to 100 mph.

Now I notice from the knowlegebase that the recommended GS300 pressures for 245/40/ZR18 tyres are 35 psi front /32 psi rear for up to 4 people for speeds up to 100 mph.

Before I try these pressures, could any one advise whether they are running 245/40/ZR18 tyres on their GS? If so I'd appreciate if you let me know what pressures you are running at and whether you have any tramlining issues. Is it worth having the repaired tyre replaced?

Any help/advice much appreciated.

On the bright side the tramlining is keeping me honest. About a month back I was treading cautiously along an uneven stretch of the A30 (dug up by the cable TV installers), and I came upon a speed trap around a corner. If I didn't have tramlining issues I possibly may have been issued my first NIP ever! I guess every cloud has a silver lining

First of all, lucky you to have a V8 under the bonnet!

With regard to your issues, I have been running a GS300 Sport 1999 model with the same tyre size, but Pirelli P Zeros.

I have never really felt the car tramline, unless the road has been dug up along the side etc.

I'm generally running at 32psi all round too. The car's handling and ride are not great when compared to E class and 5 series, but the steering shouldn't be twitchy. I find the ride to be crashy when going over uneven roads, but I don't find myself correcting the steering as you describe.

I wish you'd posted sooner. I just got my geometry checked out by Dr Bones, and it was so out of alignment. Drives great now.

Oh, and if you fit new tyres in future, I recommend the Goodyear Eagle F1s, as I've just had them put on the back. Bloody brilliant!

mki gs300 sport 245/40/18 front 275/35/18 rear. I run on 36psi all round,no problems with handling, but only 10000ks from rears.only problem is on inside lane on motorways...following ruts left by hgv

Hi,

My cars a mk1 but im running the same tyre size as you pb3.

Im got 40 psi in the fronts and 36 in the rear,theres little tram lining only like stated above on dug up roads.

chips..

Thanks for all replies to date.

From my Googling to date it looks like tramlining is a "feature" of wider tyres, with some makes particularly worse than others.

Looks like I need to book a session with the legendary Tony "Doctor" Bones of Watford.

Perhaps I exaggerated slightly when I described the twitchy steering as "bucking bronco style" but you do need to actively grip the steering and make corrections when driving over uneven roads. The steering sometimes seems to have a mind of its own when the road is uneven. Even though I haven't been in danger of running of the road, the twitching can be unnerving.

I'll have a play with the tyre pressures as well.

Peter

Hi,

Driving along the motorway yesterday along the inside lane,the road condition was very poor from all the heavy lorries/coaches using it the most.My car was tramlining but the road had sank down a fair amount I can now see why everyone drives in the middle lane

Chips..

Hi Peter,

I have a 2001 (X reg'd) GS300 Sport and it's on Pirelli P-Zeros. I have the car regularly serviced and the steering is tracked absolutely as standard. I have never yet experienced any tramlining whatsoever, and the tyres seem very good all-round, wet or dry. When they come up for replacement it will be the same, i.e., P-Zeros again.
I tend to drive quite quickly and the cornering grip is top notch. One very minor point, I do find that it's easy to spin up the rear wheels when making a brisk start in the wet.
I use tyre pressures of 36psi front and rear and it is a bit better than 32psi, more stable and less sense of lateral tyre to rim movement under hard cornering. It hasn't increased the tyre noise which is quite high but pretty much normal for such low profile tyres.

Hope this helps.
Best regards,
FastLemon