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991.2 GTS Tracking/Tyre Wear

andydon

PCGB Member
Member
Hi All

My 991.2 GTS has covered a massive 6,500 miles since new (now 3 yrs old) but at its recent MOT both the rear tyres were found to be very worn on the inside. The rest of the tyre (on both L+R) was fine, so the car passed. They put it down to tracking. I wasn't going to let the MOT garage touch the tracking so took it to the OPC. The OPC reckons I need 2 new rear tyres and tracking. Has anyone else gone through a pair of tyres so quickly (I haven't had it on a track, not many races off the line, etc....)?

Thanks


Andy


 
Hi Andy

For your car to have good handling attributes, the rear wheels usually have the geometry set with some toe in + some negative camber. So it is not just the tracking (toe angles) you need to check but both settings (toe + camber). As you have wide rear tyres, both of these settings, whilst useful to the stability of your car, also contribute to the inner edges of your tyres wearing out faster than the outer edges. This is quite common.

If you never do Track Days you can settle for Road Settings which will assist in extending the life of your tyres.

In my experience, not all OPC's are equal & some of them show a distinct lack of talent when it comes to geometry settings.

There are some very good Independent Porsche Specialists who should be able to assist you. Depending on where you are based in the UK. I would be happy to recommend someone.

Finally you do not list which make of tyre you currently have. Some high performance tyres have a softer compound of rubber, which whilst maximising grip, also means the tyre will wear more quickly. So you should select a replacement tyre which is a good fit to the type of driving you envisage doing.

I hope this helps.

Kind regards

Gary Marsh
A Need 4 Speed Ltd
07768997050
www.aneed4speed.co.uk
 
Hi Gary

Thanks for the fast response. I'm in Surrey and the car has Michelin Sport tyres on it.

I agree the tyres may have a softer compound but was hoping they would last a bit longer than this!

If you have suggestions for a specialist I'm interested.

Thanks again


Andy

 
Hi Andy

I have a 991.2 GTS and, as normal with most 911s, the inside edge of the rear tyres do wear more quickly than the outside because of the negative camber and rear toe. I suspect that the settings for your car are not correct as I would expect you to get more than 6.5k miles from the rear tyres assuming, as you say, no track days or continual, maximum acceleration. I have been getting about 12k miles from my rear tyres but quite a lot of the mileage has been European touring holidays (when we could!) and includes some autoroute mileage which will not generate as much wear as spirited A/B road driving.

I use Centre Gravity for geometry set up, they are excellent but they are in Atherstone which is a bit of a drive from where you are. They charge more than normal for a session (about £300) but do a very thorough job including an assessment drive and a test drive after the geometry has been set.
 
Hi Andy,

FWIW, I had a new set of 245 & 305 Michelin PS4S fitted to my car about 7,000 miles ago and only have minimal differences in tread wear across the rear tyres (slightly more on the inner edge, as expected), so I agree with other members that your geometry could do with checking. The geometry was checked at Dick Lovett in Swindon, when they changed my tyres, so I know that running the car on a mix of M/way, fast road and spirited B-road driving shouldn't pose a problem.

Centre Gravity are excellent but I can highly recommend Dick Lovett at Swindon and they're closer to you - it's a 200 mile round trip for me but it's more time in the car and so far I've been impressed enough to warrant the drive.
 
Andy,

interesting you have Michelins fitted, as I thought Porsche fitted Pirellis from new. (Assuming you do mean the car has done 6500 miles from new on those tyres?)
 
Hi

Yes, I had Michelins on since new. I ended up replacing with more Michelins and had the geometry "done" at the same time by Porsche Guildford, my local OPC.

Since then it has done about 10 miles due to lockdown, but looking forward to trying them out soon to see the difference!

Regards


Andy


 
I have the exact same issue with my 991.2 GTS which will also be 3 years old in May, I've owned the car since new and its just coming up to 10k miles, at my first service last year, it was highlighted to me that the rear tyres were wearing on the inside and that the alignment should be checked, but only after fitting new tyres first. The rest of the tread across the tyre was still in the region of 5mm if i remember correctly. so far due to lockdown I haven't had the chance to get it sorted, but will need to do it soon as my MOT will soon be due. The most interesting fact i found was the huge variation in costs between OPC to provide a full alignment check and adjustment. i live in Berkshire so contacted Reading OPC who quoted me over £550!! for an alignment and adjustment! i also called Swindon, Portsmouth and Brooklands who also all quoted different amounts for the check. their prices ranged from £249 - £350 and finally i called Northway (local independent) who quoted £180 (all prices includes VAT) Ive also used Centre Gravity in the past and been very pleased with the level of service and detail from them, they were quoting me £350 at the end of last year when i contacted them, but as we then entered in to lockdown once again, i couldn't justify the drive, for my car to ultimately sit on the driveway....
 
I have almost the same issue with my 991.2 GTS 4 years old and 34,000. Pirellis all round. Just become aware that apart from a nail in the rear nearside, tyre wear on the rears is very consistent now at 4-5 mm across both tyres. However, wear on the FRONTS is more severe on the insides which would be consistent with the issue of negative camber setup for handling, but seems to be inconsistent with other posts on this thread and elsewhere on other forums. So mine has greater wear on the inside of the fronts while basilbrush and others have it on the rear, on similar models. As a relative newbie to the 991 this is a chin-scratching moment.

Grateful for any further comments from the group.

basilbrush said:
I have the exact same issue with my 991.2 GTS which will also be 3 years old in May, I've owned the car since new and its just coming up to 10k miles, at my first service last year, it was highlighted to me that the rear tyres were wearing on the inside and that the alignment should be checked, but only after fitting new tyres first. The rest of the tread across the tyre was still in the region of 5mm if i remember correctly. so far due to lockdown I haven't had the chance to get it sorted, but will need to do it soon as my MOT will soon be due. The most interesting fact i found was the huge variation in costs between OPC to provide a full alignment check and adjustment. i live in Berkshire so contacted Reading OPC who quoted me over £550!! for an alignment and adjustment! i also called Swindon, Portsmouth and Brooklands who also all quoted different amounts for the check. their prices ranged from £249 - £350 and finally i called Northway (local independent) who quoted £180 (all prices includes VAT) Ive also used Centre Gravity in the past and been very pleased with the level of service and detail from them, they were quoting me £350 at the end of last year when i contacted them, but as we then entered in to lockdown once again, i couldn't justify the drive, for my car to ultimately sit on the driveway....
 
It sounds as if you may have too much negative camber on the front, the best solution is to get a full geometry set up carried out by a good independent. I would recommend Centre Gravity if you are not too far from Atherstone.
 
Grateful Terry, thanks. Atherstone might be a bit far for me but I will ask around all the same.
 
The roads in Blighty are generally poor so to maximise the life of my expensive rubber I have Porsche carry out the Wheel Alignment, soon after I have purchased new tyres. I bought my latest 991.1 in late December, then after purchasing a full set of P-Zero's, the attached Wheel Alignment Report reveals adjustment was necessary.

Download
 

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