Newbie Tire Size Help

I am about to buy a 1999 996 with 10 year old tires so, they clearly will be replaced before my arrival to take possession of the car and undertake a 500 mile drive home. My question is on size. Tire rack states the stock sizes being: Front: 225/40-18 Rear: 265/35-18 But, I have read on here where a better size to run in the rear is a 295/30-18. I know, another tire question but, any advice would be much appreciated.

Depends on the wheels. Can you post a picture or give the actual Porsche part name? I.e. Carrera II, III, etc. The Mk1 996 Carrera was stock 265 and the Mk2 was 285... pushing further on OEM wheels may cause problems for you.

Wheels on the car are the optional 18" 993 turbo wheels from what I can decipher off the options sticker. Code 408 correct?

They definitely appear to be the 993's 18" Turbo I or Porsche# 993 362 140 01 That would mean the rear wheels are definitely 10 inches wide. Personally, I would NOT recommend exceeding 285 series on the back with 10" wheels. If you had the wider 11", then 295 would be correct. I'm sure some track heads will chime in that they've put 11" wheels and 300+ series tires on the back, but personally, I think the wider tires (295 series or more) look weird on the OEM stock rear 10" wide wheels and could potentially scrub. Again, IMHO go with the Porsche approved 265/35/18 for the Mk1 on the OEM stock rear wheels.

Just replaced the PO's 285/30/19 with 265/35/18 on my 1999 and it looks much better. 285 is to wide and sticks out past the lip of the fender.

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That's a good point. If I'm not mistaken, Porsche "rolled" the fender's edge to accommodate the wider tires on the base Mk2 Carreras. And I believe there are some slight changes in the suspension components on the MK2 that freed up much needed space. Anyway, I think the point is that it's prolly better to stick with the Porsche approved 265 on the Mk1, but if you go with the 285, there may be some issues.

Thank you for the advice. I will stick with the suggested OEM sizes.

Fronts should be 225-40-18-7.5 with a 50mm offset Rears should be 265-35-18-10 with a 65mm offset The current wheels I am using are an optional wheel with the stock sizes and offset available at the time. They look really good on the car and you'll see them all over the place on the mark1 996. For what its worth I also run spacers front and back. Something like 10-15 on the front and 25-30 on the rear. No rubbing what so ever, but I also have coil overs and a ton of suspension mods... You were also able to get some factory wheels in a 17 configuration but I don't know what the sizes or offsets were for them.

You went for the red one, excellent!!! I have exactly the same wheels on mine (turbo hollow spoke 18''). I got 225/40 front, 285/30 back. They fit perfectly, got Michelin PS2 (N rated).

I did go for the red one. Well, pending the outcome of the PPI tomorrow. And I knew ahead of time that it needs tires. Road Force Balancing? I watched several YouTube videos and this definitely seems like a higher tech method of balancing than just spin balancing them and that's it.

Depending on what brand tires you buy, you may be able to split the difference and go with 275's on stock 10" rears with no rubbing issues. I have 275 rears on my '02 with 10" wheels. But others' advice is valid......don't go beyond 285.

I think I am going to play it safe and stick with the recommended factory sizes of 225/40-18 front and 265/35-18 in the rear. I chose what I hope is a decent tire given I will not be tracking the car or driving it in the New England Winters but, it may get use in the Fall when the temperatures are colder. The tire I chose was the Sumitomo HTR Z III, at least for my first set. I am hoping this is a good, safe tire and doesn't drain my budget so I can spend that money of the IMS/RMS/water pump. I will have them road force balanced as that seems like a very worthwhile investment.

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Good choice. Sumi's are good street tires and a good value too.

Good to hear. I expected to get flamed as tires choice can be a very sensitive subject. Almost as bad as talking politics, religion or blondes vs brunettes vs redheads or whatever the different preferences are for the female members.

I have Sumi HTR ZIII on my 996tt and like them. I concede that there are better tires out there, but bang-for-the-buck wise, they are very good. As for doing the RMS/IMS bearing on a 1999, man, I think I'd just let it be unless you've got a significant oil leak there. The data on replacement IMS bearings for the factory dual row is inconclusive. You may very well be replacing the factory bearing with an inferior aftermarket one, plus there is a risk that the installation could be not quite right causing problems. And the failure rate for the dual row factory bearing is generally considered to be around 1%. If you are going to do it at all on a '99, definitely wait until you need a new clutch. As for your color choice, Guards Red for the win, baby! And a little know Porsche secret is that the factory includes an extra 25 hp on all of the Guards Red cars.

I did read that the Sumitomos got good reviews and you can't beat the price. I hope they are capable of handling the extra 25 HP that comes with the Guards Red cars. I also have heard that car insurance companies charge more for insurance on Guards Red 911s because they are involved in more accidents caused by distracted, envious drivers of less sexy cars. Having researched all I can about the IMS and how the 1998 and 1999 model years used the dual row design bearing and experience less failure than the newer single row bearing I am only looking to replace it when the clutch is done. On the same note, and I know I am new to the Porsche community but, I have not been convinced that the LN Engineering solution bearing is in fact an upgrade. Especially now that they have been installed in cars for a period of time and are seeing wear on even the ceramic bearings. Even to the point that LN has recommended replacement every 50k miles. To me that is not a solution to the problem. When I replace my IMS I will go with the Direct Oil Feed bearing from TuneRS. This to me appears to be the best designed solution to getting oil where it needs to be, on the bearings. Not to turn this into an IMS options thread. Just my research and my opinion.

I run Sumi's on my BMW and like noted previously, they are good bang for the buck tires. If you are merely using the car to toy around town, they'll work just fine. FWIW the Solution is guaranteed for life, however it is $1,800 vs $800 I believe for the retrofit kit which has a 7yr warranty. Congrats on the GR if the PPI goes through!

Wow! Love the Guards Red Aero! Beautiful Car! What wing does it have?

Not sure on the wing.