Verner Posted October 20, 2020 Report Share Posted October 20, 2020 Hi guys, please forgive me for asking what is probably a very stupid question. When it comes to Wheels/Tyres I have absolutely no idea. I have a 2006 987S (Below):- I am looking to purchase a new set of rims for her and have seen these "turbo" ones on Design 911 which I like, The recommended Sizes are:- Front 225/40/18 Rear 285/35/18 According to the tyres I am currently running they are:- Front:- 235/40 ZR 18 Rear:- 265/40 ZR 18 I don't understand, does that mean I will need to get new Tyres for the new Rims, should I purchase them? Does it mean these rims are the wrong size for my Boxster? Once again, apologies for asking stupid questions, but as I mentioned before i am clueless. Any advice would be greatly received, Best wishes from North Yorkshire, Verner Link to comment Share on other sites More sharing options...
Topbox Posted October 20, 2020 Report Share Posted October 20, 2020 The tyres on the car are standard size tyres for a Boxster 987 18" factory wheels. The thing is the rear size is unusual (thanks Porsche) and there is not a lot of choice of high performance tyres in that size. So the new fronts at 225 are a bit narrower than what you have and the backs at 285 are a 20mm wider. Not sure if its wise to try and fit your exsisting tyres to your new rims. A good tyreshop will advise as I am sure some here can better than I. Often nice wheels with tyres for sale here btw, at good prices. Hope that helps a bit. Link to comment Share on other sites More sharing options...
Philc Posted October 20, 2020 Report Share Posted October 20, 2020 The 2 numbers either side of your existing valves will be the width and offset (J and ET). If using the same tyres it would be wise to get new wheels with the same figures ( although not necessary if you can work out the difference) Link to comment Share on other sites More sharing options...
Philc Posted October 20, 2020 Report Share Posted October 20, 2020 https://www.willtheyfit.com/ Just to confuse you even more🙃😆 Link to comment Share on other sites More sharing options...
Menoporsche Posted October 20, 2020 Report Share Posted October 20, 2020 Go and look at the numbers either side of your valve, front and rear. Front will probably be 8, rear might be 9, 9.5, 10. Your wheels are standard Porsche wheels so maybe anyone else with the same wheels can also do that. The wheels you listed are 10 (inches wide) at the back, I think the Boxster can handle that but you might need spacers. That style was common for 911s so the rears would be very wide, but they did come out on Boxsters briefly so Boxster sizes should be available. Willtheyfit is usually the resource quoted here. Just check those wheels are not diamond cut polished - originally they were and that finish is notorious for corroding after a few years (or months!). Painted hyper silver or similar would give much the same effect with much longer life. Seems silly to buy new wheels then paint them though... Link to comment Share on other sites More sharing options...
Philc Posted October 20, 2020 Report Share Posted October 20, 2020 For reference I have a set of replica turbo 2 alloys but in 19". The rears are 10 wide (cant remember ET) and are fitted with 265/35/19 tyres. The tyres are budgets and don't have any rim protection, but the tyre stretch means when lying them flat it's wheel rim that touches the floor and not tyre sidewall. They clear the suspension without spacers though. Link to comment Share on other sites More sharing options...
Menoporsche Posted October 20, 2020 Report Share Posted October 20, 2020 ooh, bet your cheeks clench when parking close to a kerb... Link to comment Share on other sites More sharing options...
Philc Posted October 20, 2020 Report Share Posted October 20, 2020 40 minutes ago, Menoporsche said: ooh, bet your cheeks clench when parking close to a kerb... They are trashed, and I mean curbed inside and out! by the previous owner not me🤣. I replaced them with OE base 17s for comfort and livelier handling on skinnier tyres. Just keep the 19s for storage/emergency spare wheels now. Link to comment Share on other sites More sharing options...
½cwt Posted October 20, 2020 Report Share Posted October 20, 2020 @Verner the sizes listed in the ad are 986 18" rim tyre sizes. (rear is 265 not 285 you typed...) Nice looking rim BTW. Your current tyres would fit on these rims with no problem, however someone more familiar with the 987 sizes should be able to comment on whether the offset (the ET number) will give any issues but I would imagine not. I have some 911 GT3 look a likes on my 986 and the tyres are well clear even with the 91 offsets but they do sit out in the arches somewhat compared to the standard ones, like having spacers but not needing them, but I echo @Philc above who mentioned rim protection, even with the protection lip on the tyre they don't quite protect a 10" rim when you lie it down so take care. It was suggested to go to 275 wide on the rear on mine next time which will still fit fine on the car without spacers. 17" Before & 18" After below Link to comment Share on other sites More sharing options...
sa utah Posted October 20, 2020 Report Share Posted October 20, 2020 Once again my “As the factory intended” OEM OCD is going crazy ! get your factory wheels refinished and stick to the correct size tyres. Those “Turbo” wheels look wrong. Wrong I tell you ! Link to comment Share on other sites More sharing options...
MickH Posted October 20, 2020 Report Share Posted October 20, 2020 Just to balance the argument, imo wheels are one of the best upgrades you can have visually to the car. And really make it your own. Link to comment Share on other sites More sharing options...
zcacogp Posted October 22, 2020 Report Share Posted October 22, 2020 On 10/20/2020 at 9:04 PM, sa utah said: Once again my “As the factory intended” OEM OCD is going crazy ! get your factory wheels refinished and stick to the correct size tyres. Those “Turbo” wheels look wrong. Wrong I tell you ! Well said. I'm definitely with this guy ^^^^^^^ Factory wheels in the smallest size, with narrowest tyres possible. It's (almost) ALWAYS the best combination for handling on any car ever. Link to comment Share on other sites More sharing options...
½cwt Posted October 22, 2020 Report Share Posted October 22, 2020 7 hours ago, zcacogp said: Well said. I'm definitely with this guy ^^^^^^^ Factory wheels in the smallest size, with narrowest tyres possible. It's (almost) ALWAYS the best combination for handling on any car ever. Exception - Impreza Turbo consensus was definitely better on 16" rim with the correspondingly reduced profile. The 15" were marginally more comfortable but not better handling. Many manufacturers do however ruin ride comfort by going to stupid low profiles on the tyres. A thought, if narrow tyres with small wheels handle better, why do they put the biggest rims and widest tyres they can get on GT cars, touring cars and tarmac spec rally cars? (Before anyone says anything, 13" rims in F1 are an anachronism due to ancient regulations ignoring tyre technology) Link to comment Share on other sites More sharing options...
Philc Posted October 23, 2020 Report Share Posted October 23, 2020 8 hours ago, ½cwt said: A thought, if narrow tyres with small wheels handle better, why do they put the biggest rims and widest tyres they can get on GT cars, touring cars and tarmac spec rally cars? (Before anyone says anything, 13" rims in F1 are an anachronism due to ancient regulations ignoring tyre technology) "Handle better" is subjective. Outright grip isn't. Link to comment Share on other sites More sharing options...
½cwt Posted October 23, 2020 Report Share Posted October 23, 2020 1 hour ago, Philc said: "Handle better" is subjective. Outright grip isn't. To be fair some said the the original Impreza was a triumph of grip over handling. Link to comment Share on other sites More sharing options...
gIzzE Posted October 23, 2020 Report Share Posted October 23, 2020 18 hours ago, ½cwt said: A thought, if narrow tyres with small wheels handle better, why do they put the biggest rims and widest tyres they can get on GT cars, touring cars and tarmac spec rally cars? (Before anyone says anything, 13" rims in F1 are an anachronism due to ancient regulations ignoring tyre technology) There is a fine line with tyre sizes. What are you wanting from a tyre? I guess we are looking for as much grip as possible while getting feed back from the chassis so we can feel what it is doing? Is that the same on a smooth track vs the typically poor road surfaces that we tend to get in the UK? What we are looking for with a tyre is the most amount of force possible from the contact area we have pushing down onto the surface, we ultimately want to try and increase the overall friction. The problem with simply adding wider wheels and tyres is you are also adding contact area, but if you have not increased the downforce you are left with less force per square inch biting into the surface and therefore you actually end up with less friction/grip. Combine this with less chassis feel that always comes with larger tyres and you can end up with a car that you can carry less speed in. And that is on a super smooth surface, get on the road where you have some pretty poor surfaces and going to bigger wheels/tyres can give you less 'bite' from the rubber, and before you know it you have a tyre that simply ends up skipping about too much on fast corners that are anything other than billiard table smooth. Plus, because you have reduced chassis feedback once again you tend to hold back more, that is just natural. That is one of the reasons the base 987 Cayman running 205F and 235R is said to be one of the best Porsches all round cars to really enjoy UK roads with. The combination of having to keep it in the 4000+ rpm range and the right sized tyres to cope with our crappy surfaces. Obviously all cars will vary on what the 'ideal' is, and it is as much about geometry, the type of rubber and one of the most important, air pressures for a given size and car weight. But far too often modern cars are over wheeled for UK roads and don't add anything but looks. Link to comment Share on other sites More sharing options...
Verner Posted October 26, 2020 Author Report Share Posted October 26, 2020 Many thanks for all your kind replies. I will take time to read them all and digest fully. 🙂 It's great to get expert advice, Thanks guys, Verner Link to comment Share on other sites More sharing options...
½cwt Posted October 26, 2020 Report Share Posted October 26, 2020 8 hours ago, Verner said: It's great to get expert advice, That's a hell of an assumption here!!! Good luck Verner, hope you like what you decide on. Link to comment Share on other sites More sharing options...
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