Wheels/tyres - some thoughts please ...

[pottman]

Folks,

I've recently replaced the front tyres (with the appropriate N2 rated Michelins) on my 997.2 C4S and almost immediately noticed a vibration from the steering wheel when driving at motorway speeds. I've subsequently had the front tyres balanced (twice), yet still the vibration continues and on further investigation am being told that it is the rear wheels/tyres that are damaged and causing the problem.

This has apparently been tested via replacing my tyres/wheels with an alternate set to check if the vibration disappears.

I accept that I live in a land of potholes and speed humps, but am generally very careful with this and have never kerbed my wheels, however I am now faced with replacing the two rear wheels /tyres at £x,xxx. The upside is that I can get a full set of tyres and sport classic wheels for £x,xxx + not much.

So ..

- why would I notice the vibration only after new front tyres have been fitted
- surely the vibration should be due to something on the front end - not the back end
- am I the only one who has experienced this issue

[Ian_UK1]

pottman said:

Folks,

I've recently replaced the front tyres (with the appropriate N2 rated Michelins) on my 997.2 C4S and almost immediately noticed a vibration from the steering wheel when driving at motorway speeds. I've subsequently had the front tyres balanced (twice), yet still the vibration continues and on further investigation am being told that it is the rear wheels/tyres that are damaged and causing the problem.

This has apparently been tested via replacing my tyres/wheels with an alternate set to check if the vibration disappears.

I accept that I live in a land of potholes and speed humps, but am generally very careful with this and have never kerbed my wheels, however I am now faced with replacing the two rear wheels /tyres at £x,xxx. The upside is that I can get a full set of tyres and sport classic wheels for £x,xxx + not much.

So ..

- why would I notice the vibration only after new front tyres have been fitted
- surely the vibration should be due to something on the front end - not the back end
- am I the only one who has experienced this issue

A rear wheel imbalance can be felt just as keenly as a front wheel imbalance, but as you say, if you've only had the front tyres replaced, why would there suddenly be a rear wheel imbalance?

Where did you get the front wheels balanced? Have you tried taking the car to a different tyre specialist? Maybe a different firm, with a different balancer, will be able to get them right. If you take the car to one of the better tyre specialists, they should also be able to balance your rear wheels and check them for concentricity, run-out, buckling, any damage etc.

If it does turn-out that your rear wheels aren't as round as they should be, have a chat with Chris at Exel Wheels. (Chris is very well known on here for his sterling re-finishing work on various Porsche wheels. He's done several for me and I can't recommend him highly enough). It's quite possible Chris could have your existing wheels re-rounded or otherwise 'trued-up' for a fraction of the cost of new wheels. He did this for me on a set of 25-year-old BMW split-rim BBSs (that now look like new and are fitted to my '85 635CSi). These things were almost square - as well as shockingly badly corroded - before he took them away! (That's not too much of an exaggeration either)! It may also be an opportunity for you to have all your wheels refurbed and/or have the colour/finish changed.

Best of luck - and it would be interesting to find out how things work out for you where this issue is concerned.

Edited by Ian_UK1 on Sunday 21st September 19:29

[pottman]

Thanks. Some good thoughts here. I have now tried two different companies to rebalance the wheels - both of whom I would expect to know what they are doing, so perhaps my rears really are damaged.

I too have used Chris before and didn't realise that he may be able to "re round" them. Definitely worth exploring.

Will let you know how I get on, I currently can't decide if I am aggrieved at spending the money or excited about having a new set of sports classics ..

[Orangecurry]

Sounds like bks to me. If the only thing that has changed is at the front, then the problem is at the front.

One possibility is that one of the new front tyres is not round - not that uncommon.

[pottman]

Ian_UK1 said:

Best of luck - and it would be interesting to find out how things work out for you where this issue is concerned.

So I'm now feeling a lot poorer, but rather pleased with the way my C4S now looks and indeed handles ... no vibration at all.

Going to see if I can get the old wheels refurbished and then maybe sell on or use as winter set.



Ho hum.

[Ian_UK1]

Now that's a proper, lateral-thinking solution!

Are they the Porsche-supplied 'Fuchs-style' or genuine (non-Porsche-approved) Fuchs?

Either way, they look the mutts on the 997 - great choice.

[pottman]

Ian_UK1 said:

Now that's a proper, lateral-thinking solution!

Are they the Porsche-supplied 'Fuchs-style' or genuine (non-Porsche-approved) Fuchs?

Either way, they look the mutts on the 997 - great choice.

Thanks. I'm very pleased with the result, albeit an expensive one as they are Porsche Sport Classics.

Maybe if I can sell my old wheels it might ease the pain a little!