Cocked the handling up - any ideas?
Discussion
2009 Astra 1.8.
No fireball by any stretch of the imagination but, before I had 2 new rear tyres fitted, I knew it's limits and how it would react in certain situations.
However, since having 2 new Dunlop tyres fitted on the rear the 'handling' has gone to pot.
I think it's now suffering from, basically, the new tyres outperforming the fronts.
It's demonstrated by, at say 60/70mph, and just flicking the steering from left to right. What follows is that the front will change direction then there's a sort of squirm where it seems that the back then catches up. It's quite un-nerving at first, especially on the same day as changing when the fitters had only put 31psi and it was bucking around like a kangeroo. Previously the pressures were 36 all round - as recommended for 'economy driving' in the handbook. Pumping the new rears up to 36 improved things a lot, but it's still there.
Rear are Dunlop Sport BluResponse (V rated) and the fronts are Bridgestone Turanzas (H rated).
When I was buying the new Dunlops I could get the V rated versions for the same price thinking it would improve handling.
Obviously now I know I should have perhaps gone for H rated to match the fronts.
Do you reckon messing with pressures will improve matters - perhaps reducing the fronts?
Or, should I just concentrate on wearing down the fronts as quickly as possible so I can get some more Dunlops?
No fireball by any stretch of the imagination but, before I had 2 new rear tyres fitted, I knew it's limits and how it would react in certain situations.
However, since having 2 new Dunlop tyres fitted on the rear the 'handling' has gone to pot.
I think it's now suffering from, basically, the new tyres outperforming the fronts.
It's demonstrated by, at say 60/70mph, and just flicking the steering from left to right. What follows is that the front will change direction then there's a sort of squirm where it seems that the back then catches up. It's quite un-nerving at first, especially on the same day as changing when the fitters had only put 31psi and it was bucking around like a kangeroo. Previously the pressures were 36 all round - as recommended for 'economy driving' in the handbook. Pumping the new rears up to 36 improved things a lot, but it's still there.
Rear are Dunlop Sport BluResponse (V rated) and the fronts are Bridgestone Turanzas (H rated).
When I was buying the new Dunlops I could get the V rated versions for the same price thinking it would improve handling.
Obviously now I know I should have perhaps gone for H rated to match the fronts.
Do you reckon messing with pressures will improve matters - perhaps reducing the fronts?
Or, should I just concentrate on wearing down the fronts as quickly as possible so I can get some more Dunlops?
doogz said:
What did it do before you fitted new tyres, when you flicked the wheel left to right?
The steering wheels respond first, since they’re the ones you’re asking to work.
I don’t quite understand the problem.
It's hard to describe really. The steering wheels respond first, since they’re the ones you’re asking to work.
I don’t quite understand the problem.
Previously it did what you say, steer and change direction, simple.
It does the same now, but there's a sort of 'squirm' after the change of direction has happened, a sort of sideways shimmy - as if the tyre walls are flexing at different rates.
Or the tread blocks flexing?
205/55 x 16 - so there's definitely plenty of sidewall. 
Softer sidewalls? Yeah, this is what I'm thinking.
I could see that causing what's happening.
It only happens if I 'make it happen'. So under normal driving you'd never noticed and it's something you could easily manage.
But I know it's there now so, under the right circumstance, will expect it (well at least while they're still new).
Softer sidewalls? Yeah, this is what I'm thinking.
I could see that causing what's happening.
It only happens if I 'make it happen'. So under normal driving you'd never noticed and it's something you could easily manage.
But I know it's there now so, under the right circumstance, will expect it (well at least while they're still new).
Edited by Fastra on Thursday 13th June 12:58
robinessex said:
Maybe this. Many years ago I mixed makes on a Lotus Europa. Nearly scared myself to death on the first fast corner. Turned the car round, and went back and had 2 more (same make) tyres fitted. Problem solved.
Thank god for the that then. 
Thought it was just me and my soft, sensitive arse.
Yep, 91 load rating all round.
Not checked the nuts, will do now though.
Will definitely rotate them round too.
Fortunately there's a by-pass near to home that doubles up nicely as a test track.;)
I have had a similar experience in my previous Astra.
Michelin Pilots from new, put 2 new Falken ZE912 on the rear and basically the same thing happened as now.
Eventually solved by getting some more Pilots on.
Not checked the nuts, will do now though.
Will definitely rotate them round too.
Fortunately there's a by-pass near to home that doubles up nicely as a test track.;)
I have had a similar experience in my previous Astra.
Michelin Pilots from new, put 2 new Falken ZE912 on the rear and basically the same thing happened as now.
Eventually solved by getting some more Pilots on.
real4star said:
Does it tell you the number of ply's (is that even a word?) on the sidewall ?
6 ply fronts and 8 ply rears perhaps (IIRC eco tyres are stiffer to save fuel)
Checked the plie info this morning.6 ply fronts and 8 ply rears perhaps (IIRC eco tyres are stiffer to save fuel)
No idea what it all means but here you go:
Bridgestones:
Tread - 1 Polyester.
Sidewall - 1 Polyester + 2 Steel + 1 Polyamide
Dunlops:
Tread - 2 Steel + 3 Rayton + 1 Nylon
Sidewall - 1 Raych (or is it Ratch??)
So, not exactly like for like to make an easy comparison.
Can I assume that the addition of Steel in the Bridgestone sidewall therefore makes it stiffer - I have no idea what 'Raych' is though.
Right.
Just had a phone call from a very nice man at Dunlop (I put my concerns to them via email through their website), and as a few of you have already said the Dunlops do indeed have a soft sidewall makeup and he knew exactly what I was trying to describe.
He explained that whilst badged 'Sport' these particular tyres are infact more aimed at comfort, so aren't as hard as their other 'Sport' models.
He also went onto say that it's quite a common complaint/issue and he'd actually like to see more tyre tests conducted using different combinations to give more of a real world outlook on things. I myself can't ever remember (apart from 4 Avons on the wifes Micra) replacing all four tyres at once on any car I've owned.
So, in conclusion, he recommended NOT increasing the pressures past an already high 36psi but swapping them rear to front instead.
He also asked me to let him know, as he always hears complaints but never really gets to know how anything gets solved.
He also agreed that screwing the hell out of the Bridgestones so that I could get another set of Dunlops was a great idea.
In hindsight I should have just got the same Bridestones (only an extra £10) as already on, but you always think you can improve things don't you.
Just had a phone call from a very nice man at Dunlop (I put my concerns to them via email through their website), and as a few of you have already said the Dunlops do indeed have a soft sidewall makeup and he knew exactly what I was trying to describe.
He explained that whilst badged 'Sport' these particular tyres are infact more aimed at comfort, so aren't as hard as their other 'Sport' models.
He also went onto say that it's quite a common complaint/issue and he'd actually like to see more tyre tests conducted using different combinations to give more of a real world outlook on things. I myself can't ever remember (apart from 4 Avons on the wifes Micra) replacing all four tyres at once on any car I've owned.
So, in conclusion, he recommended NOT increasing the pressures past an already high 36psi but swapping them rear to front instead.
He also asked me to let him know, as he always hears complaints but never really gets to know how anything gets solved.
He also agreed that screwing the hell out of the Bridgestones so that I could get another set of Dunlops was a great idea.
In hindsight I should have just got the same Bridestones (only an extra £10) as already on, but you always think you can improve things don't you.
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