jbaker136

For our 2014 981 Boxster S with 19" wheels, I am looking to replace the OEM Goodyear EAGLE F1 ASYMMETRIC 2 tires with Michelin Pilot Sport 4S's. However, the P4Ss in the factory size of 265/40ZR19 for the rears only comes in an M0 (Mercedes) manufacturer spec while the front only comes with no manufacturer spec.Michelin and Tire Rack say that this will be perfectly fine to run on our Boxster S but mixing rubber compounds front and back seems like a bad idea so I am looking for alternate tire size options. The closest size for the rear would be 275/40ZR19 with no manufacturer spec to match the front. With that I could do either the default 235/40ZR19 or the 245/40ZR19 for the fronts. The 245s and the 275s are only 0.3" and 0.4" larger in diameter (about 1.2% and 1.4%) then the OEM size so I don't think this should be an issue at all but I would be interested in some second opinions. I did confirm that the OEM 19" wheels have rim widths in spec for the wider tire sizes as well. Thanks in advance.

Jeff

Drew_K

If you're worried about having to use Porsche rated "N" tires, I wouldn't limit yourself. The non-N tires are used on plenty of other sports cars. Find the size that fits and go with it. And the 4S's are an amazing all around tire, as I'm sure you already know.

pashapaul

I was presented with the same issue last month when replacing original 19" Pirelli PZ0's on 2014 981BS - finally went with the 4S's although non Porsche spec and I am pleased with the result

GT4John

I run 4S's on my GT4 and LOVE them. You should be fine.

jbaker136

I am not worried about running non Porsche N rated tires. I was worried about 1) the correct OEM size for the rear, 265/40ZR19 ONLY comes in a Mercedes "M" spec and 2) The closest size I can get that is not some other manufacturer spec like the "M" would be 275/40ZR19 and I was just confirming that this slightly larger (about 1.3% larger diameter) rear would not be a problem with fitment. Thanks

Jeff

jbaker136

What size did you go with front and rear and how is the fit? Thanks

Jeff

pashapaul

went with stock sizes on my 19" - fit just fine

fast1

I've been a customer of the same Porsche dealership for over three decades, and have a good relationship with almost everyone there. I talked with a couple of techs and the service manager about replacing my 19" Pirellis. The consensus was PS 4S with or without the N rating.

jbaker136

Did they tell you when you had them installed that the rear tires in your size are a Mercedes spec tire? See the highlighted row in the picture below from Michelin. It just seems weird to me to run a Mercedes spec tire compound in the rear and a standard Michelin spec tire compound in the front but perhaps I am making too much out of this. It would be great if I could just get front and rear of the correct size with either Porsche spec all around or no spec all around.



235/40ZR19 has no manufacturer spec and 265/40ZR19 has Mercedes spec compound. Porsche spec PS 4S are only in 20" wheels.

jbaker136

I agree and that would be great if it was possible but you cannot get the rear tire size (265/40ZR19) with the N spec or without the N spec. It is only made in the Mercedes "M" spec. And the front tire is only made with no manufacturer spec so if you go with the correct size for a 19" wheel then you will be mixing Mercedes spec in the rear with no spec compound in the front.

Jeff

mike-l981

If you're not going to compete in Autocross at Parade, go with the 245/40-19 and 275/35-19. They fit the rims just fine. Presumably your local region allows you to run the larger size in Stock, if you autocross.

fast1

The combination that concerns you is the one first listed on Tire Rack's site for your car. I find it hard to believe that Tire Rack would recommend a combination that would be incompatible for your car. OTOH it's your money, so buy what gives you the most piece of mind.

One final thought. Given your concerns it may be better to go with another tire manufacturer, ideally with N rated tires. Tire Rack lists three different manufacturers offering N rated tires for your car. Unfortunately none of them are rated highly by Tire Rack. Tire Rack has a decision guide to help its customers select the tires that are best for their needs. I used their guide for a 2014 Boxster S, and listed wet road handling, dry road handling, quietness, and tire wear as most important and price as least important.Tire Rack's first recommendation was Michelin PS 4S, followed by Continental and Bridgestone . The Porsche N rated tires for your car didn't make the top three.

So clear as mud, right?

If it's any consolation to you I know two 981 owners who have about a year on their 19" PS 4S tires, and up to now they couldn't be happier. They both had Pirellis and told me that the PS 4S are far superior. It could be that OEMs will have a longer tire life, but only time will tell.

fast1

Jeff - You are making an assumption that may or may not be true: tire compounds for the M0 265 rears are different than the 235 fronts. Only Michelin would know the answer to that question. A certainty however is that Michelin does not recommend ordering tires that differ in size from your OEM tires. I copied the following from Micheln's web site:

Can I buy a tire size different from the one that was original equipment on my vehicle?

For maximum safety, Michelin recommends to only replace your tires with the same size recommended by the vehicle manufacturer.

Some advice

• Never choose a tire that is smaller in size or has less load-carrying capacity than the tire that came with the vehicle.
• Tires should always be replaced with the same size designation — or approved options — as recommended by the vehicle manufacturer.
• The correct tire size designated for your vehicle should always be verified with the information in your vehicle owner’s manual in the glove compartment or on the tire information sticker on your driver’s side door.

jbaker136

Thanks for the input. I definitely moved away quickly form the idea of non OEM size tires after talking with a my local Porsche dealer service manager who was previously the shop foreman . He strongly advised against it saying the PSM is calibrated for and works best with tires of the manufacturer size (26.4" and 27.4"). As far as the MO1 compound goes, I did talk with Michelin and they said manufacturers in general have input on the belt design and tread compound when designing manufacturer specific tires.

Jeff

jbaker136

I really wanted the PS 4S tires and after Tire Rack assured me the MO spec rears would be no issue I went ahead and ordered those. Thanks everyone for all the great input.

Jeff