New tyres - full geo alignment required?

[RBD914 v2]

So I had both rear tyres replaced today, Pirelli p zeros, worn on the outside edges to an illegal state after 11,500 miles.

My thoughts after replacement was that a full geo alignment check might be in order due to the uneven wear - I got 15,000 miles out of the Pirellis on my previous Boxster 2.7, however the GTS is putting more power through the rears so maybe 11,500 miles is acceptable?

However on inspection of the brand new Pirelli replacements, the tread depth on the outer third of the tyre measures 6mm compared to 8mm on the rest of the tyre! Presumably this is to counteract the negative camber the car runs. So the tyres will wear out first on the outer edges, anyone else found this?

Anyway, as a result of this finding, I am now questioning whether a full geo alignment check is necessary? How do you know if a car needs it / would benefit from it?

Any thoughts and opinions welcomed as I don't want to spend time and money unnecessarily....!

Car handles, drives, steers and stops perfectly by the way, so no obvious wayward symptoms needing addressing.

[Araf]

I reckon it is probably fine and you've been enjoying corners too much.   What are the edges on the front like?

[Toeside]

I would agree 11500 miles sounds good enough for a car with that power  

[RBD914 v2]

9 minutes ago, Araf said:

I reckon it is probably fine and you've been enjoying corners too much.   What are the edges on the front like?

Fronts about half worn evenly on both tyres....just the rears that wore on the edges.

[RBD914 v2]

2 minutes ago, Toeside said:

I would agree 11500 miles sounds good enough for a car with that power  

Yes that's what I thought, thanks for your input!

[Araf]

Just now, RBD914 v2 said:

Fronts about half worn evenly on both tyres....just the rears that wore on the edges.

If the inner shoulders are also worn then I would look at your tyre pressures.  If not - and the rest of the tyre was around the 2mm mark, I'd say you've got yout money's worth.  

[RBD914 v2]

Normal wear on inner shoulders, rest of tyres were around 2mm mark, just the outer shoulders were worn to almost slicks!

As you say, just about got my money's worth!

So no Geo required in your opinion then?

[RBD914 v2]

Running 30 psi all round...

[Araf]

23 minutes ago, RBD914 v2 said:

Normal wear on inner shoulders, rest of tyres were around 2mm mark, just the outer shoulders were worn to almost slicks!

As you say, just about got my money's worth!

So no Geo required in your opinion then?

No I think that's probably about right.  Maybe you could increase the tyre pressure by 1-2psi, but then it depends how often you check them.  If it's once in a blue moon, then check them more often and leave the pressures at recommended level. 

[Greenman]

The first groove (outermost) on P zeros is not a primary groove, they will always look more worn on the outer edge due to this.  In addition they tend to wear slightly quicker on the outside edge.  

When I was looking  for mine last summer I noticed this on the car I eventually bought, I mentioned it to the rep who suggested it was normal and showed me three other 981s they had in stock plus I checked two other customer cars in the car park, every one had more wear on the outer edge than the inner on the rears. I have 12k on mine and I'm at 3mm, I reckon I'll get maybe another 2k out of them.

[RBD914 v2]

13 minutes ago, Greenman said:

The first groove (outermost) on P zeros is not a primary groove, they will always look more worn on the outer edge due to this.  In addition they tend to wear slightly quicker on the outside edge.  

When I was looking  for mine last summer I noticed this on the car I eventually bought, I mentioned it to the rep who suggested it was normal and showed me three other 981s they had in stock plus I checked two other customer cars in the car park, every one had more wear on the outer edge than the inner on the rears. I have 12k on mine and I'm at 3mm, I reckon I'll get maybe another 2k out of them.

Thanks for this information, the wear on mine seems pretty normal then.

[mneil]

981s with 20" wheels, sports suspension 20mm lower. Rear s lasted about 16K, wore on the inside, the outer 4" still looking well above the wear limit marker. Geo still was fine...spirited use of the right foot perhaps causing rear suspension to compress. Ooo er not me officer?.

[RBD914 v2]

You did very well to get 16k - what brand of tyre was that?

[That986]

10 hours ago, RBD914 v2 said:

Running 30 psi all round...

I don't have a GTS but that sounds wrong to me. My 986 has 29 on the front and 36 in the rear.

[Kevin G]

7 minutes ago, That986 said:

I don't have a GTS but that sounds wrong to me. My 986 has 29 on the front and 36 in the rear.

Your pressures are correct for a 2000 986s. The handbook recommended pressures for my 2.7 981 are 29 front and 30 rear. 

[mneil]

Was running the standard Pirelli .

[That986]

2 hours ago, Kevin G said:

Your pressures are correct for a 2000 986s. The handbook recommended pressures for my 2.7 981 are 29 front and 30 rear. 

Would have thought they'd be higher than that, interesting that the earlier cars require higher pressure in the rear tyres. 

[Greenman]

1 hour ago, That986 said:

Would have thought they'd be higher than that, interesting that the earlier cars require higher pressure in the rear tyres. 

Are the earlier cars on 265 rears?  If narrower then they would typically have higher pressure.  981 recomends 33psi or 30/31psi(comfort mode) on 20 inch rims if you stay below 150mph.  

[That986]

27 minutes ago, Greenman said:

Are the earlier cars on 265 rears?  If narrower then they would typically have higher pressure.  981 recomends 33psi or 30/31psi(comfort mode) on 20 inch rims if you stay below 150mph.  

There's one of those stickers under the front bonnet that states with the 265/35/18 tyre at the back they should be 36psi.  

[michelin]

There is only one place I go to and that's Center Gravity. I've used them for years and Chris franklin is a perfectionist. Enough said. ?