New Tyres, Very unstable at speed?

[samu23]

Hi Guys

I had some new Uniroyal rainsport 2's put on the back of my MR2 last week and since then when travelling over 60mph the car feels very unstable. Almost like its very very windy, and its moves around a lot.

Is this normal? As it can be very scary at times. A full set up and alignment was done a few months before the new tyres as I had my coilovers fitted. All the suspension components are in good condition.

The old tyres were cheap and on the limited but they felt al ot safer than these brand new tyres. I did check the pressures and they were quite high 37psi could this be effecting it?

Thanks


Sam

[cvega666]

A full set up and alignment was done a few months before the new tyres as I had my coilovers fitted.
Sam

I think you should repeat full alignment.

[HighwayStar]

If they're standard sized rears... 225/50/15 they should be at about 32/33 psi so I'd say a little high as they are... more importantly how are they compared to fronts which if standard should be about 29/30psi. Balance is key. Try different pressures and if no joy look to alignment again only once you've checked over for suspension damage or wear.
Good luck.

R.

Edit: just noticed you're in a rev1... standard 205/60/14 rears? Whatever I'd still have a good play with pressures first. ... Any probs cornering?

[2mad]

Hi,

37 psi seems way to high to me . . After trying out a few different tyre pressures I found 30psi front and 32psi rear the best for stability/handling on car.

Also as far as i'm aware tyre pressures should be staggered with the rear tyres having 1 or 2 psi more than the front.


Good luck, Kev.

[samu23]

Yes its a rev 1, however it has 17" 7J wheels on, put the same size tyres on that came off, and tbh the old cheap ones felt a lot more secure, no real problem cornering, its just at higher speeds on a dual carriageway/motorway.

Ill let the pressure down to about 33psi, see if that helps.

Thanks for the responses.

Sam

[dantheman]

If it is veering left and right on the motorway its not the tyres and its not the pressure, its the alignment

[gt4mayhem]

The same thing has been happening to me for a couple of months. At slow speeds she's fine but at higher speeds she really starts to wobble but I have not had an alinement done since owning her. Also she managed to work her way through some new Toyo proxies on the rears very quickly.
But know what ya mean bud don't trust it into corners or on the dual carriage way..... Is alinment an exspensive thing? Did have tracking done a little while ago and spigot rings checked and they were fine
I hope it is alinment that makes the car drift a little left a little right as It is scary as helll driving a turbo when this happens.
Will get this sorted first thing Monday if that is what causes the mr2's to do that.....

[cvega666]

full alignment should not cost more than 60-90 quid (paid 60 quid in Elite tyres in London.). It's well worth the money. I just did it on my car (also, never done it since I've owned it).

[bobhatton]

What are your tyre sizes front and rear? The rear wheels should be wider than the front not both 7" wide

[Quigonjay]

if they are directional (which i beleive rainsports are) have they been fitted the right way round?
do you have spigot rings? not unheard of for a wheel to be put back on without it

[samu23]

Yes the tyres are 7J all round which I know is not the best way to have things. I changed the tyres as the car is going up for sale soon and I do not feel comfortable selling it as it feels unsafe.

It did have spigot rings on when it went in, I will check they are still there tomorrow! I think I will then lower the pressures and then get a full alignment done and I will report back.

Cheers for the help.

[raptor95GTS]

new tyres are always xxxx for grip for the first few hundred miles and the car will snake over surface changes and road camber angles. Just go easy, scrub them in and you'll be fine But as said 37psi is a bit high

[Baker]

new tyres are always xxxx for grip for the first few hundred miles and the car will snake over surface changes and road camber angles. Just go easy, scrub them in and you'll be fine But as said 37psi is a bit high

as he said.
Dont waste your money on an alignment just yet!!
seeing also as its been done recently.

[Ho7617]

How's the wobble at speed? Did you cure it?
I just bought a rev2 and it suffers also with being vague and floaty on the front over 70-80 mph, handling is great under these speeds...

[Adam86]

I run my rev 3 turbo on standard 15s with proxies. I have 34psi front and 38 rear. Higher pressure gives less tyre wall flex and makes it feel more stable. New tyres on the rear always feel horrid though.

[Willenium]

Running 215/35/18 tyres all round on ours with 32psi up front and 38psi at the rear. Feels more or less ok at low to moderate speed but if you start to get a shift on it seems to get a bit wobbly in the steering and it's not very confidence inspiring. Need to get some camber bolts in order to complete our alignment but I am curious to find out what else is the matter. About how much wider is it recommended to go on the rear tyres in relation to the fronts?

[HighwayStar]

Rev1.. 10mm, rev2+ ... 30mm. Personally I think a 20mm difference is best for the most neutral handling.

R.