m1cassels

After giving up waiting for tyes from Crossroads, went out and bought new pair of F1's as rear tyres were illegal. Well chuffed with price and fitted them to rear of MY01 Wagon. Still have original supplied Bridgestone Potenzas on front which didn't like much cos of tram lining, but still have about 3000 miles left.

HOWEVER, although sharper on slow corners, when at higher speed (i.e. anything over 60) the back end sways and slews around like a bl**dy Volvo estate. What's going on? Seriously disconcerting and well annoyed having spent over £200 on what evryone generally says are the best....

Is it because I've mixed different tyres - find hard to believe it would behave like that?

Tyre pressure? Currently 32/33 front rear?


HELP! Anyone any ideas on set up, pressures, similar experiences?

MC

Adam M

are we talking about an impreza here?

if so,

you now have different makes front to rear on a four wheel drive, with completely different compounds, and different wear rates and different diameters.

this is a complete no no on a four wheel drive.

You will be placing load on your centre diff (not much) all the time. This increase the temp of its oil and its wear rate.

not good at all.

would expect handling to be affected, on top of the fact that these tires take a good few hundred miles to bed in.

m1cassels

Yes it's an '01 Wagon as stated.

Appreciate your comments. Different diameters? Not sure what you mean by that though.

Surely if you go from nearly bald rear tyres to new F1's, you wouldn't expect the back of the car to begin to swing and sway like a pendulum when you make the slightest steering movement? Nearly lost it altogether a few times at the weekend, not doing anything particularly aggressive either.

ozzy

I'm still a bit sceptical about swapping all 4 tyres at the same time due to diff problems, but I'm no mechanic so what do I know.

New tyres are cr@p until you scrub them in, but I'd have expected them to be more grippy than a set of bald OE's.

Suppose you could always swap the F1's too the front of the car and see how the handling is affected. I'd obviously recommend you test them somewhere safe in case you do lose it.

Stefan

pugoetru

I agree that you shouldnt mix tyres my legacy got 2 punctures in 1 week and i just put 2 part worn tyres i had lying in the workshop on it the handling was very twitchy brakes locked too easy was no fun i will be changing all 4 in future

Boarder1

I had the same problems when I fitted two new front tyres (GSD-2's) and left the Bridgestones on the rear.

On two separate occasions the back end wanted to slide out, made me very nervous driving the car. I replaced the two Bridgestones for another set of GSD-2's and the car grips and handles as it should now!!

I definitly would not mix tyres on a Scooby again!

Mark

ozzy

If you mix ' match different tyres, with different compounds, tread depths, pressures, etc.. then Yes, you will affect the handling. Just too what degree this will be depends on the difference between the fronts and the rears.

I would only have expect the car to become tail-happy if the rear grip was reduced OR the front-end grip was improved.

Sounds to me like they just aren't scrubbed-in yet.

Have you driven the car in the dry or in the wet (after today's little downpour in Scotland)?

Stefan

m1cassels

That's exactly what is worrying me - I would expect the tail to be a bit wayward if the older balder tyres were on the rear, but they're not.

Have only driven in the dry this weekend, not been out in the wet yet. Might be even more scary.

Do you think higher/lower pressure might help (currently 33psi)

Claudius

Could be due to different load ratings as well. I'd try and lower the rear tyre pressure.

ozzy

Tyre pressures are worth experimenting with. I haven't run the new Goodyears (just the previous incarnation).

My Toyo's repsond well to higher pressures (but 34psi equal all-round). I ran my old Goodyears @ 32psi all-round.

I would try reduce the rear pressure, to induce a little more grip. Say 33psi FR, 30/31psi rear.

I can certainly feel the difference a 3-4 psi make in the tyres, so it's worth experimenting.

Stefan

Mungo

Rear pressures look a bit high - fronts generally should be 3-4 psi higher unless you're carrying people in the rear seats.
Probably also that silicon crap left on the tyres from where they get them out of the mold.
Shouldn't be too much of a problem with better tyres on back than front - likely to swap ends if the other way round.
Don't worry about the different radius thing - that is what diffs are there to sort out.

m1cassels

Ta. Will try the different pressures at the rear and see how it goes. Just have to wear down the fronts faster and replace soon, then have 4 alike.

Scoobs_4ever

Going throgh a similar experience myself.

I changed all 4 tyres for GSD3's and I did notice an increase in understeer in slow corners and huge amounts of squirming under heavy braking compared to the SO2's I had on before.

Things are improving after 500 miles. Must say though, the wet weather traction of the F1's is much better.

Jza

Your tyre pressures are wrong!

Shouldn't it be 2.2 bar front and 2.1 bar rear? thats what my manual says..

Jza

m1cassels

What's that in old money?

Anyway, my manual says front 32, rear 33 and that ain't working at the moment.

ozzy

There is no exact right pressure as such, it's just that the manual shows Subaru's recommended pressures for even tyre wear and for the OEM tyres.

Every tyre and car will respond slightly differently to tyre pressures, so you should always start with a decent setting then adjust too suit.

You may find that the manual states a particular combination that just so happens to respond well to a particular tyre (like the new F1), but that would be luck and not exact science.

When I bought my Toyos, I stared with the same pressures as my previous Goodyear F1's (32psi all-round IIRC), then when I didn't like the handling I experimented. I'm now running 34psi all-round, but I may experiment a little more by running 34psi front, 32psi rear.

Anyway, have you tried different settings and has it made any difference to the handling?

Stefan

m1cassels

Just changed last night to 32 front, 29 rear to give it a try. May be a bit low for rear. Haven't had a chance to try yet so have to get out on the open road.

austen_wrx

Its the soft side walls of the F1's compared to the stiff potenza's! I have just changed my 4 Potenza's for F1's. It felt like the i was driving on blamonge to start with. I have now put 34 up front and 36 at the rear and it feels better but its still there. The f1's do stick like $hit to a blanket but they do not feel as nice to drive on as the potenza's. I am getting used to it and after the initial wobble entering the corner they feel fine, but i wish someone had told me this before as i would have probably spent £400 on a set of Toyo's or put the bridgestones on again!

m1cassels

That's exactly what I found. Tried 29 at rear but not much better so will try your suggestion.

Are the Toyos any better for stiffer side walls?

I can't understand why everyone harps on about how fantastic F1's are when they roll around like this. At first it was like driving a 110 Land Rover with the pendulum/blamange motion. From what I can see so far the Potenzas were much firmer, although grip not so good, and you don't have that "I'm driving a Volvo Estate" feeling.

Stuck with them now, so have to get used to it I suppose.

austen_wrx

I'd rather have the planted feeling than the wallowing w@nk that these give!! The lower profiles probably don't suffer as badly, so i am assuming that the all the people harping on about them have 35 or 40 profiles! I just gonna screw the living daylights out the car and try and wear them out asap!

ozzy

I've had Pirelli P-Zero's, Goodyear Eagle F1's (not the very latest) and Toyo Proxes T1-S's on my RB5 and the F1's were a much better tyre that the others.

Pirelli's were 205/45/17 and the other two have been 215/40/17's. The Toyo sidewalls do flex a little more than the other two, but it's definetely doesn't feel like driving a big lumbering estate car. Not to me anyway.

Austin_Wrx,

If you'd have asked about the sidewalls, maybe someone would have answered you and saved you wasting money

The moral of the story is don't believe everything you read on here, especially when it comes to performance differences as everything is subjective. I like the F1's, you don't - it's as simple as that.

Stefan

austen_wrx

I never actually realised how much difference there could be! I have never kept a car long enough (or had a car go through tyres as quickly) before to change all 4 tyres at once and see what effects it has.

"The moral of the story is don't believe everything you read on here, especially when it comes to performance differences as everything is subjective" - i have learnt this now, cheers ozzy

BT52b

I really like them so far, much much better grip and less reluctance to turn in than the original Bridgestones.

Toyos have much softer sidewalls than the F1s and they feel a bit odd when they flex IMO

Mark

[Edited by BT52b - 10/07/2003 14:35:28]

ozzy

Thank you; I'm glad I've converted you to my way of thinking

Stefan

greasemonkey

Making sweeping judgements about any tyres before they're thorougly scrubbed is never a good idea, so it may simply be a case of giving them time.

It's already been said that mixing tyre makes/diameters/compounds/wear rates on a four wheel drive car is a bad idea, and depending on the disparity, thus could, in large part at least, explain what you're experiencing.

If the difference in rolling diameter is big enough, it could be wind-up through the transmission - effectively making the rear wheels try to overtake the fronts all the time (could also explain the "sharper" feeling at lower speeds, as the car will effectively have more rear-wheel-drive bias).

The centre diff will try and sort it out, but its viscous coupling will in turn try and maintain the torque split. That will give it a hard time, cause less than ideal handling, and could concievably damage it if you leave the situation for long enough.

It could also simply be that the Goodyears give a different "feel" to the notoriously stiff sidewalled Bridgestones you had before.

Easiest way to find out would be to put another set of Goodyears on the front...

[Edited by greasemonkey - 10/07/2003 17:33:20]

m1cassels

If I had a habit of throwing away money, yes.

Opinion seems to be divided as to whether a few millimeters difference in tread, because that's what it is, will really cause that much of a problem with the diff. If that were the case then every time your front tyres wore down, which they do much faster than the rear, you'd be creating a similar problem in reverse.

I think it more likely just the different type of tyre, as I have learned from the responses received - very helpful. Until I started this thread I'd never seen any mention of the still/soft side wall question.

"Making sweeping judgements about any tyres before they're thorougly scrubbed is never a good idea, so it may simply be a case of giving them time."

Not a sweeping judgement/statement - just a personal experience - that's what I posted for, to get opinions.

ricardo

I've never felt the F1's to have any wobblyness at all, that's in 205/50 16. After P-Zeros they seemed slightly more supple, but much more planted. No squirming, no wobbles. 33 front, 32 rear, digital gauge.

It isn't just a few mm of tread depth the diff is having to cater for, some tyres have a different rolling radius quite separately from their actual radius, this probably depends more on the construction and compound than the actual size.

I'm with greasemonkey - too much of a mixture to work well. You'll have to get another pair before long, why not take the hit and do it sooner rather than later.

Another possibility - could something have been damaged/altered when the car was jacked to fit the new tyres ?

exesspeed

well a new one today tvr have been testing tyres, and the track, on their the goodyears over heated too far and they lost traction ,they tested many other makes too, and had no probs at all, and ive seen the tyre,s and they have visibly melted when the other makes look sound, so you can guess they prob wont be order in any, i was but after seeing them compaired to the others no way, and yes i know tyres are driven much harde on the track and all tyre,s show visible sighns of the rubber rolling up, but not like the one,s i saw, i know its nothing in comparison compaired to your problem but im lettin you know what ive seen and was told the conclusion may be they should be called BAD YEAR, LOL