Worrying handling, no, scary handling..

[Zed]

Hi guys,

So after much discussion and deliberation, decided to scrap the runcraps for Goodyear F1 As2's as the rear MIchellin SP2's RF's were done. The same RF's remain on the front as there's 5-6 mm remaining but the intention was to replace these with the Goodyear's when the time comes....I only took this approach having read numerous posts here and elsewhere regards running fundamentally differing tyres between axles, some have experienced no issues whatsoever and others have so forgoing the obvious views about this, here's the issue...

After a few days with the new rears, the steering felt very nervous and twitchy, especially at speed. Worse than that, TCS is engaging when cornering and the front appears to be scrubbing with the inevitable braking under TCS engagement. I've had alignment checked and all is good with the exception of a slight rear camber adjustment (drivers rear). The wheels are 108's 18 and staggered and in good condition. The steering input seems way too big for the turn required, more so at town speeds, switching on sport mode helps and a little at speed. Lowering the pressures, 32/34 has also helped but the concern is running the front RFT at 32.

Basically at speed the front is very pointy and nervous, maintaining straight requires a fair bit of steering input. TCS kicks in when cornering at speed and a little on tight corners while pushing a bit. It seems worse turning right for some reason?

Mechanicals have been checked, all linkages, bushes and mounts are good. Never had this issue so obviously it may be the different tyres but worried about changing the fronts to Goodyears and still having twitchy issues and losing confidence in handling when the car was previously planted, knowing when the rear would start to break traction and the back feels so planted at the moment. Or try move the Goodyears and switch back to SP2 RFT's.

Either or, for safety, it's driving Miss Daisy mode for now, hopefully some good advice to follow as garages all have their own opinions and btw, not one of them has raised an eyebrow over the mix of tyres!

Cheers guys!

 

[StevenH72]

How many miles have you covered in the tyres, could it be that they just haven't quite "scrubbed in" yet?

 

[Squiddie]

Can you post all tire and wheel specs (aspect ratio, offsets etc)?

Are you sure the total outer diameter isn't different between front and back?

 

[mr wilks]

Ive ran a mix as yours but the opposite way around , no issues but I would get the RFs off the front asap , you should solve the problem that way
You could experiment temporarily by switching the fronts to back & see what happen's ? You wouldn't run that way permanently but it may lead the way to your solution :?

 

[gannet]

There have been others on here in the past reporting similar handling traits when mixing RFT and non RFT tyres front to back.

Personally I wouldn't mix...

 

[paulgs1000]

How long have you been running the GY rears?

There's been a great deal of posts regarding the GY Eagle F1s needing more miles than expected to bed in - 200 miles or more.

If you haven't done this mileage yet, I'd wait to see how they perform once well scrubbed in.

Like others I had GY Eagles fitted and at first thought I'd made a big mistake but I stuck with it and now I have GY all round and will have them fitted again - excellent in wet and dry.

Hope this is your problem. (I run 34 rear and 32 fronts with GY all round (staggered))

:driving:

 

[Zed]

Cheers guys thanks for the replies.

The GY's have been on the car for three weeks now, limited mileage though, probably 2-300 miles? Few hot starts with TCS off to scrub them in further or just keep the miles coming?

Seems most running this different Tyre setup have FT's on the rear with normal brand x on the fronts with no issues whatsoever. I'm (was) intending to replace the fronts but if the general feeling is just ditch them, would soon find out if that's the issue or not...or as suggested, swap them round (255 front, 225 rear) as a test.

255/35/18 (GY F1 As 2 normal) - 225/40/18 (Michelin Sport P2's RFT), regards total rolling radius/diameter, I've only replaced with same size?

I'll grab the 4=wheel alignment report and re-post, slight adjustment on the fronts, biggest was offside camber, less so nearside but both replaced Tyre's had worn on the insides.

One point I forgot to mention was with regards to sticky steering, transpired it was the front FRT not sitting on the rim properly which was fixed, air leaking and pressure was down which presumably caused the sticky wheel and it only happened at slow/parking speeds.

Do you guys think the different tyres front and back would cause the excessive steering input, god forbid it's a steering mechanism issue! Steering if anything felt vague before the rear tyre change, I'd put that down to lack of rear grip, well worn and uneaven. I'm obviously no suspension expert and hope for a reasonably low cost fix...missing not pushing my Zed!

 

[jnwright71]

Hi Zed,

I had the same problem as you having swapped out Bridgestone RFT on the front for Pirellis (part worn). Handling was scary and steering all over the place. I had alignment checked 3 times, all bushes checked, lollipops replaced and still no joy. So I bit the bullet and swapped the Pirellis for GY F1s and the problem disappeared. I was amazed, but there you go, these cars simply don't like certain tyres / tyre combinations.

Now I run 31 psi front and 33 rear (rears are standard Pirellis).

I paid £198 fitted for the pair of GYs - best money I have ever spent.

Hope this helps.

Cheers, James

 

[ranski]

I had exactly the same by wish the traction control was disabling while going (slowly) round roundabouts.

I had a hunter alignment and all was sorted

 

[csl1973]

I'm swapping my rears for non rfts as they are very low on tread. They are being replaced with bridgestones s001s non rfts. The fronts are bridgestones rfts but will be replaced once the funds are replenished. Hope I don't suffer the same problems.