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Discussion Starter #1 (Edited)
Hi guys,

I've had my 2015 86 for nearly two years now, and all of a sudden after getting the rear tyres changed the balance of the car feels really off, mainly at higher speeds. It used to feel planted and controlled even up to naughty speeds. Now I feel like wind is hitting the car subtly even though it's not - driving in a straight line is harder now - and the car feels 'floaty' and steering input feels way too twitchy at that speed. I feel like I have to make a lot more effort to keep it straight than I did before the tyre change. It doesn't feel particularly safe, although I wouldn't want to exaggerate. It doesn't feel like the comfortably 'tight' ride I had before where I felt very safe at high speeds.

Car is stock, except I changed all four tyres to pilot sport 4's over a year ago. I do a lot of driving though, and enjoy putting her through her paces so the rears needed replacing, and I made the shit decision of using my Dad's local garage because it was cheap and times are tough. I should of known better. I don't actually know what system they used, but will find out. Got a lot of other things going on in my life at the minute and this is all a learning curve. Either way, from a little online digging, I'm thinking they didn't do the alignment properly. Would love to hear anyone's thoughts.

I'm running the tyres at 32 psi at the moment. But I've always run them a bit lower than the suggested so I don't think that's part of it.

I'm in Portsmouth so also looking for any recommendations for a good garage to get the alignment checked with a proper Hunter system...Formula One Autocentre use one so might opt for them.

Anyone got any ideas?
 

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What does 'wheel change' mean here? You can get this type of problems when alignment is off but since when does a wheel swap require realignment? Maybe if the offset changes a lot but generally wheel swap/tyre swap does not change the geometry and no realignment is needed. Wheel balancing on tyre swap yes, but if wheel balance is off you get vibrations.
PS4 has an inside and an outside to be verified but it doesn't appear to be directional.
 

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Discussion Starter #4
What does 'wheel change' mean here? You can get this type of problems when alignment is off but since when does a wheel swap require realignment? Maybe if the offset changes a lot but generally wheel swap/tyre swap does not change the geometry and no realignment is needed. Wheel balancing on tyre swap yes, but if wheel balance is off you get vibrations.
PS4 has an inside and an outside to be verified but it doesn't appear to be directional.
Yeah, what am I on about - tyre change! I wrote this post last night a little tipsy and there you have it. Duh.

Tyre change. The wheels came off for the tyre change, I figured or heard there's a chance they could put them back on with the weights incorrectly placed or something?
 

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Discussion Starter #5
Wheel change or tyre change? A wheel or tyre change doesn't need an alignment as you don't touch the suspension components. The obvious one is to check pressures. Are all 4 tyres the same?

Yeah the tyres are all at 32 psi.

Could I just be feeling some subtle artifact of having more worn front tyres, and brand new rear tyres? Like the wear on the front tyres will give them a slightly different grip?

Could putting tyre pressure up to the recommended 35 psi stabilise the ride a bit?
 

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Discussion Starter #6
Wheel change or tyre change? A wheel or tyre change doesn't need an alignment as you don't touch the suspension components. The obvious one is to check pressures. Are all 4 tyres the same?
Could checking pressures post drive vs when the tyres are cold give me slightly inaccurate readings?
 

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Wheel weights would cause a vibration, but otherwise shouldn't affect how the car feels. Same tyres? Probably best to check pressures when cold so all are the same temp. I guess the other thing to note is that new tyres take some time to wear out the coating they get, this does reduce grip so will create an unbalance front to rear. This usually wears off after some mileage.

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Discussion Starter #8
Wheel weights would cause a vibration, but otherwise shouldn't affect how the car feels. Same tyres? Probably best to check pressures when cold so all are the same temp. I guess the other thing to note is that new tyres take some time to wear out the coating they get, this does reduce grip so will create an unbalance front to rear. This usually wears off after some mileage.

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Yep same tyres. Okay...I'll just put it down to me over thinking it mixed with a bit of what you mentioned - the fact that they're new and I must be noticing the grip difference. Roads have been pretty slippy lately too.

Thanks for input mate :)
 

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not that changing tyres has anything to do with this (i agree with the other replies), but might be worth checking out that car's rear shock absorbers. they can make the car feel like it's on air, or not planted, if they're worn/leaking/etc. if it's not that, then might take some miles for the tyres to bed in. the only other thing, which you've ruled out, is incorrect (very high) tyre pressure after replacing tyres.
 

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Discussion Starter #10
not that changing tyres has anything to do with this (i agree with the other replies), but might be worth checking out that car's rear shock absorbers. they can make the car feel like it's on air, or not planted, if they're worn/leaking/etc. if it's not that, then might take some miles for the tyres to bed in. the only other thing, which you've ruled out, is incorrect (very high) tyre pressure after replacing tyres.
Ah okay, thanks mate, will see if I can get that checked at some point, just to make sure.

I took a drive up to Chichester from Portsmouth yesterday, got the tyres up to 35psi first, nice surface, and it felt better...so now I'm thinking I might of just been imagining it. Maybe there was some wind gusts or something, the day I got suspicious and as I said the road was greasy. And I guess with this car it's easy to notice slight changes - as I'm guessing it probably is just that the rears need running in a bit and whatever difference in grip that has caused I'm picking up on.
 

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Tyres usually take 100-200 miles to "bed in" - it used to be put down to the mould release compound residue left on the surface, but I think that was debunked. Whatever the reason, I always find brand new tyres feel a bit skittish for a hundred miles or so.
 
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