17" Tyre sizes, when stock isn't an option.
 

Hi guys, new here and have a question about tyre sizes.

My 2001 Boxster S Tip is in need of new tyres. I am in South Africa, so we only use summer tyres here year-round. When I bought the car about 2.5 years ago, it came with the incorrect tyre sizing on the stock 17" wheels - 205/50R17 front and 225/45R17 rear instead of a 255/40R17. The current tyres are also run-flats. I decided I will change tyres when needed. Now is the time and I am having an incredibly difficult time finding the stock sizes as a staggered set.

The only tyres I can find locally that will be stock sizing are:
- Bridgestone Potenza Sport (super soft and will get little mileage, plus $$$)
- Dunlop SP Maxx Sport 050+ (not really a Dunlop fan and reviews don't inspire)
- Davanti DX 640 (not a familiar brand and reviews are inconsistent - very cheap as well)

Nothing else has a staggered set and the Porsche dealership can order me a set of Michelin Pilot Sport 2s, with a lead time of a few months as they are being specially made on order - at almost double the cost of any other option from a tyre shop.

Ideally, I'd like to put on Goodyear Eagle F1 Asymmetric 6s - but they don't make a 255/40R17 in the tyre.

A 245/40R17 would make the diameter of the wheel 9mm smaller than the stock front 205/50R17. A 225/45R17 is closest in relation to the front and compared to the 255/40R17, and I can't say that the current setup has been anything less than confidence inspiring with great handling.

Would a 225/45R17 on the rear be my best bet if I can't get a 255/40R17 for the rear?

https://i.ibb.co/2Ys1fgsk/Boxster-S.jpg

Those are great questions. However, gonna need much bigger pics of the car.

Thanks Starter!

There is a reason Porsche engineers sized it that way. You probably won't like the handling with narrower rears. I don't blame you for getting off run-flats. They are terrible.
Are you unable to buy online? I would look for Contiis or their cheaper version, General GMax, but those Yokohamas would probably be great as well.
Quick search showed these: https://www.amazon.com/225-45R17-CONTI-EXTREMECONTACT-SPORT/dp/B0BFKYP9KL/ref=sr_1_5?crid=1SIAQU7TO0NPN&dib=eyJ2IjoiMSJ9.d0u g08P5cjXt-P1AvF9wKA-YdR2Glo-FaIQMQbW9mI9YOIDawDqo123UOuSs27sykW92qrnZOSYeaAqvf d4p0xGVksDHirUZgcvUx7-T0SNDWtPshtSVYcdR666YPMna8WYf-jtR2KYdW9d4wGsn1x5Ymnn5rzCUBP1CAl9nCiLlS9rVlMlqH9S lAHTpuB1U0a0prx80WaswTdgL_ADt7GMrzl012THUjMjF-5jKOYkUN955McaVFSZ6CrF6aoFt-8cxuTo3nhvONkNBRD0NsKiqRwbypanSpkUmaFw9z30.DvoXzsu 9pPHFrbOSOaBxK_ooNt-Q0XDhGIM-LdNpwK8&dib_tag=se&keywords=continental+sport+cont act&qid=1743599743&sprefix=continental+sport+conta ct%2Caps%2C114&sr=8-5

I'm sure the rears are available there as well.
Lastly, I don't know anyone using Goodyears on a Boxster (though obviously someone is somewhere.)
Good luck!

Thanks Newsguy! I'm all too familiar with the engineering decisions, hence why I want to go to a 255/40R17 on the rear. Unfortunately, down here at the tip of Africa we don't have the same ease as the US and Europe when it comes to getting what we want. Amazon is still in its infancy here. I've been to all the tyre shops and the Porsche dealership here, and besides the three not so ideal sets plus the Michelins from Porsche in the previous post, I haven't had luck in finding a staggered set.

The handling, even with the old Bridgestone RE050 run-flats and 225 on the rear has been amazing. Ever so slightly twitchy - but then I see people talk about using wider fronts to offset the understeer inherent in the handling with stock sizes and I don't have any of that in my car. The rear is definitely not super loose, but there is almost no understeer present. I've got over 10 years racing experience in various cars, and I always prefer a looser rear. I would describe the handling with 205/225 front and rear as very neutral, with a bit of twitchiness with harsher inputs on the steering wheel.

To me the big thing is that I want to utilise the 8.5J rim, and using a 225 on it doesn't look 100% right to me, although the handling is great still.

I'm just looking for a solution that will work, as I want to get back to driving and enjoying the car ASAP.

Haha, posted on IMGBB for forum use... I need to take some pics of the car again soon as autumn is rolling in down here now.

Here is a mobile phone one taken in the plantations in the Lowveld area of Mpumalanga, South Africa - gorgeous sweeping roads running to the Blyderiver Canyon.

https://i.ibb.co/BHHNHMwZ/986-Forum-Pic.jpg

As Starter noted: please enlarge your pictures. We can't see the car or the rest of South Africa.

@alfaquad - the forum software doesn’t play well with certain pictures. Please resize yours. Thanks.

See official TUEV-document for tires attached, gives you the alternatives.

Edit: When looking at the pictures, "The Ballad of Lucy Jordan" from Marianne Faithfull came to my mind....

I would try the Dunlop. Personally I had great fun with the Dunlop Sportmaxx on my BMWs. It was an older generation tyre, but I am just assuming they did not mess up a good tyre.

Compared to Bridgestone RE050A it did give slightly less all out grip, but it was much easier to read the tyre.