Mis-matched tyres

D

darren_rigg

Member
 York, UK
Hello everyone, I'm new to this forum and would appreciate some advice please.

I've just bought a z4 coupe 3.0si which is fantastic in every regard except once you get above 50mph the front end feels very loose and the car is thrown off line significantly by the slightest bump (is this tramlining?)

I think this is down to the tyres the car is fitted with. Front left is a Bridgestore potenza re050 run flat, front right is a Gerutti DS810 (Never heard of them but I dont think it's a run flat but it is rated 92Y)

On the rear are two General Altimax which have plenty of tread on them.

Front tyres are 225/40R18 and rears are 255/35R18 which seems correct.

I think the problem is the mixture of run-flat and non run-flat at the front. Has someone experienced similar problems who can confrim this is the problem before I go out and purchase more tyres.

I've seem the forum likes Falken 452/453's is this still the case? I think you should have quality tyres on a car like this and am not looking for budget tyres. I'm also not considering changing the rears at the moment, is there any reason to?

Thanks in advance.

Darren
 
Non-Run and Runflats should never be mixed on the same axial and there are those who say they really shouldn't be mixed on the front and back.
 
Sounds a pretty wicked combination. A run flat and a Gerruti ditch finder on the front and a couple of unheard of on a Zed General tyres on the back.

You're a brave man.

At least they're the correct sizes.

I don't this the 452's are available anymore. That's why I went for Vreds.
 
Unless you want to throw in £500 + for a full set of matching rubber i would start by getting a decent pair of front non -runflat & take it from there.
Lose the rears whenever you feel flushed .
I have ran runflat rear non runflat front with zero issues over 5000miles & TBH the majority of us would struggle to notice the difference on the rears whereas the fronts are night & day in comparison
http://www.mytyres.co.uk/cgi-bin/rshop.pl?s_p=Avon-ZV5-225_40-R18-92W-XL-with-Rim-flange-protection&details=Ordern&typ=D-104746&cart_id=85246540.110.9289&ranzahl=4&Breite=225&Quer=40&Felge=18&Speed=W&weiter=40&kategorie=6&Ang_pro_Seite=20&sort_by=preis&Transport=P&dsco=110&sowigan=So&m_s=3&rsmFahrzeugart=PKW
would be a base to start from :thumbsup:
 
I also run run flats rear non run flats at the front, I do not experience any issues and have been like that for 18 months. You might want to get the front bushes looked at. This could be aggravating your wonky set up.
 
Thanks for all your replies. I've never mixed tyres on the same axel before and mixing run-flats/non run-flats seemed wrong.

I'm going to get the fronts changed as a matter of priority now and will check the bushes out too. The rears are non-runflat so will see how they go once the fronts are done.

I'm pretty furious with the dealer who sold me the car. I've never had run-flats before so was not aware of the problem.

thanks again

Darren
 
I'm also in the boat of having non runflat rears and runflat fronts and have done over 30k on them with zero problems.
(I have just changed to non-runflats on the front tho, but for no other reason than the tyres needed replacing)

however, you shouldn't ever mix runflats and nonrunflats on the same axle. the drive characteristics of the two tyres are different and you're bound to have issues - especially on a steering axle!
 
You have all the advice you need on the tyres.

Once fitted check all the bushes are in good condition then and tyres settled in then get a full geometry set up. You can't do normal front wheel alignement on Zeds and they need weight added, 3/4 tank fuel and so on.

Search Hunter Alignment on here.

That will cure all your tramlining too.
 
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