Excessive Rear Tyre Wear - Bridgestone Potenza RE050A

[hielliot]

Hi All,

I have an '02 Boxster S facelift running 18" lobster claws.

I brought some new rear tyres at the end of January 2017, and decided to stick to what was already on it when I brought it late summer 2016 - Bridgestone Potenza RE050A 265/40ZR18 (101Y) at the rear. During the summer they seemed to have great grip and performance in the dry and light damp, but I noticed they became much worse during the winter with bad tramlining and poor cold grip and (at the time) put this down to tyre wear. Plus they were one of the cheapest N1 rated tyres I could find.

The car had a full alignment at Revolution Porsche in March 2017 and during summer the handling of the car was fantastic.

As I have two other cars, the car was not used much in early winter and then I was away for a month in December, so just getting back into it now and I (and the Mrs who was a passenger at the time) have noticed the cold grip and tramlining is shocking when the tyres are cold and the outdoor temperatures are around 2-6 degrees. They do get better with some careful driving to let the tyre warm up, but still way too firm a compound for winter temps. Doing some research now I have learnt they are strictly summer tyres and this is pretty typical of these tyres... not a massive problem for me as its a third car, its not driven in any ice/snow but I do need to drive it once a week or so on a fine/milder day to keep the battery ticking over, and would like to feel I am not risking my life each time I drive in colder weather.

I checked the pressures, and these seemed OK (currently running 29 front, 36 rear) and then measured the tyre depth and was shocked at what I saw!

After only 2,500 miles in less than 12mths the rears are now down to 3 - 4mm across the tyre , with the very outside (not main three central) groove at 1.5mm. They are wearing evenly across the tyre, if anything slighly more on the outer edge, but within a mm of each measurement across 3/4 of the tyre. An average new tyre would come with 8mm of tread depth (although one spec sheet I have seen for this tyre would suggest 10mm). At this rate I am likely to only get another 6months or 1,500 miles out of them, which in my view is pretty poor.   

The car has been driven mainly on single carriageway A roads on nice days for my 25mile each way commute, with a only two bits of spirited acceleration from roundabouts on dual carridgeway (purely to get the splash lubrication to the IMS, officer ) on my commute. No burnouts/wheelspin/loss of traction, and they have not been on a track day (yet!).

Is this normal for these tyres to wear this quickly?

I need to replace the front tyres soon (due to age - they came with the car and are coming up 6 years old). The fronts still have about 4.5-5mm on them (about 3.5mm on the outside edge) and they have performed and worn well over the past 12mths, so im tempted to stick to the same for the front only, but then I dont want the same again on the rear, and should I be mixing tyres even if I stick to N1's?

Does anyone have any recommendations for good 18" rubber for the 986... maybe something with a slightly less soft compound, but still a summer/performance tyre. I want to do a couple of track days this year and cant afford to shell out for new tyres every 12mths. Ideally I want something that will last a couple of years with around 2,500 annual mileage plus a couple of track days, at a similar (or only slightly higher) pricepoint as the Bridgestones, in a premium brand and ideally N rated. Do they exist??

Thanks  

[bpj]

The short answer is that no, it's not normal for them to wear that quickly given the usage the car has had.

If the rest of the car is healthy, it sounds like you could have excessive toe on the rear. Alignments aren't always performed correctly and I'd be temped to get it checked again.

Michelin Pilot Sport 4 is the best road tyre you can currently buy for the 986 - they'll be fine on the rear until the fronts need replacing.

[the baron]

I had a similar issue with Continental’s similar mileage and they were shot, I had the wheels aligned but didn’t  make much diffence, when  I got new tyres I had a “Hunter” alignment and it was found the alignment was way off hence the excessive tyre wear.

its worth paying the extra to get the Hunter alignment.

 

[Bluepork03]

Don't know if it'll make a lot of difference, but the rear tyres on 18" wheels for a 986 are supposed to be 265/35s, not 265/40s as you currently have.

[mikefocke]

Another factor is the weather. It isn't the temperature in the air that matters but the temperatures of the ground as it contacts the tyre especially as you are just starting out and the flex of the tire hasn't heated it up yet enough.  And the overnight temperature the tyre had cooled to. Even the temperature of the ground the car was parked on.

Tyre materials are a compromise between grip and wear,  Summer max performance and winter grip are two entirely different compounds. Use of the wrong tyre was a contributing factor (my inattention because I was glancing at a yellow Boxster by the side of the road was another) to my sliding into a stopped truck and totaling my first Boxster. Nice sunny day, just above freezing and the compound used in the tyres was so cold it didn't deform and become grippy as it would in warmer weather. You'd be amazed how there are small pockets in the smooth surface of the tread blocks of a tyre in the summer.

It is possible to get an alignment that favors tire wear over grip if you ask an expert for that.  I found a guy who set up racing cars so he knew the effects of various settings on a Porsche and he got me to a wear biased setting while still being within Porsche specs for my second Boxster since it had been cupping its rear tyres. Not what everyone would choose but still what I wanted and my replacement rears (Michelin) were perfect 5 years and 20k later when I replaced them because of age and not wear.

The Potenza RE50A is not a tyre rated highly for long wear.

[Menoporsche]

Your car is 15 years old, you'll have so much play in various suspension links I really wouldn't worry about N rated at this point. 

Your wear sounds excessive to me.

Michelins are considered the mutts on here but they last so long for low-mile cars; I will get Goodyear Eagles when I change mine, cheaper but good enough for my very limited mileage.

[Boxstercol]

Sounds excessive to me.

I've had 15,000 miles out if the rears of Michelin PS2's on my 987. Now on Goodyear Eagle F1's but a bit early to tell as only done about 5,000 on them, I don't think they will last as long as the PS2's, but they're considerably cheaper.

[Anker BS]

Nobody has asked how they wore! Inside, outside, middle? Are the insides or outsides scalloped? The point and type of wear are clues to why the wear occurred.

[edc]

22 minutes ago, Anker BS said:

Nobody has asked how they wore! Inside, outside, middle? Are the insides or outsides scalloped? The point and type of wear are clues to why the wear occurred.

Because the info is largely already provided. OP has written tyre has worn down to 3-4mm across the tread apart from at 1.5 mm at the outer edge. 

I don't know this tyre particularly well but many tyres are constructed in such a way that the deepest tread is in the centre and the edges have less tread. This can give the impression of uneven wear.