Help selecting the right size spacers for 997 wheels on a C4S

Greetings I bought my car with the lobster claw 997 wheels on it, and no spacers. As some other members quickly pointed out, it would benefit from spacers to get the wheels properly flush with the fenders. Can anyone help me figure out what size spacers I should be using to get the proper factory look? The rear wheels says: 11Jx19-ET51 on the back side of it. The part number is 997.362.162.00 I just realized I should have checked the front as well... Thanks in advance! Charlie

Charlie, Check the back of your OEM lobster forks for front and back again. I thought the stock offset for the 997 was the following... Front: 19x8 ET57 Rear: 19x11 ET67 If they're ET51, then more than likely didn't come off a 996, but rather a Boxster or Cayman. OEM rear offset for the C4S is ET45. The front offset is ET50

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Thanks for the help. I actually took pics of the rear wheel (see attachments). They're definitely ET51. I assumed they were 997 due to the part number (see attachment) but since they were on the car when I bought it, I have no way to know what car they actually came from. I managed to check the fronts without removing the wheels using my phone's front facing camera. The front wheels are: 8Jx19H2 ET 57 Did the C4S come with spacers from the factory? I'm trying to figure out what size spacers I need for these wheels to get a factory look in terms of fender/tire alignment. Cheers Charlie

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The C4S came with BBS "Turbo Look II" and didn't have any type of spacers since the wheels were custom made for the car. Front: 996-362-136-01 8Jx18 H2 ET50 Rear: 996-362-142-01 11Jx18 H2 ET45 Have you measured the current wheels' edge to the finder edge in mm? That may help of course. But IMHO, I would try a simple 5mm spacer which is about 1/2" out. You will also need long lugs too. Cheers!

Thanks for the info B3freak! I just measured from the top of each fender: front wheels 3.5 CM from wheel lip 3.0 CM from outmost edge of tire rear wheels 2.5 CM from wheel lip 2.0 CM from outmost edge of tire When I bought the car the dealer said that this car had came with the Turbo Technic wheels originally. Maybe those required a spacer? Regardless if the factory fit was ET45 rear and I currently have ET51, does that mean I need 6mm spacers to get a precise match? Also - I'm not sure the math makes sense. Wouldn't it take a 12mm spacer to move it out 1/2" Thanks again Charlie

Your rear lobster forks may not need a spacer since the 19-51 will extend 7mm more than the 18-45. I'd be more concerned about the inner clearance - calculator says 19mm less clearance. Go here to check yourself: http://www.1010tires.com/Tools/Wheel-Offset-Calculator#

Here are a few pictures of front and rear currently... The pics of the front are upside down... because RennList is just deciding to flip those pictures for some odd reason - even after editing them locally to be upside down thinking it would flip them right side up, they're still display upside down. Sorry.

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Maybe they meant the 18" "Sport Techno"? 996.362.136.51 front 8J18 H2 ET50 996.362.142.52 rear 11Jx18 H2 ET63 I don't see a "Turbo Technic" in the Porsche ref book ebay example: http://www.ebay.com/itm/GENUINE-PORS...8AAOSw9N1VpmI2

Hard to tell from the picture. They really don't look bad from what I'm seeing, but if you want the rear wheels to hug the fender's edge, then you need to determine what is a safe increase. If you do use spacers, don't forget your longer lugs. :-)

On my 996 c2 I had lobster forks on it and the fronts needed a 15mm spacer and then lined up perfectly. The tires were 235/35/19's. The rears don't apply to yours since my offsets were for a narrow body on the rear. Fronts should be the same though.

Here's pics of it... the one where the car looks yellowish is before the spacers. DE09DB76-57A6-4C07-99A8-831A94986D52_zpss7clta21.jpg EF71345C-A852-4262-974E-48E7822D3121_zps0q3ujhio.jpg 808556BF-FBDD-4BE0-AB04-E2CB83D6F6FA_zpsyafgmppm.jpg

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What rear tire size are you using? Im planning to order some 315/25r19 (Toyo or Nitto)

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Wouldn't the larger offset extend less? A smaller offset means the outside edge is pushed out farther. Larger offset wheels require spacers.

295 or 305 on 11 is good, 315 is too big and will bubble out, not good.

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Yeah...got confused with wheel diameter. what are the widths?

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Those were 295/30/19's and fit fantastic. I don't think I could have gotten bigger than a 305 in there without some modifications.

Awesome thanks for all the info guys! You're right, they were sport techno!

Alright. Just a couple more questions (hopefully)... Does anyone know if these are negative or positive offset? Mine both say ET before the number. If they're consistent it should be as simple as just subtracting 1 from the other to get the proper spacer size, right? Based on the thread this is what I've compiled: Stock C4S Wheels: Front 50 Rear 45 Sport Techno (what my car came with) Front 50 Rear 63 Lobster forks (what I have currently) Front 57 Rear 51 So if they're consistently either positive or negative offset, getting a 7mm in the front and 12mm in the rear would line them up with where the sport techno wheels were? That makes sense, until you get to the rears for the sport techno and the stock wheels. I've gotta believe the sport techno wheels had spacers to line them up with the stock offset - because the numbers don't make sense currently. Finally - will having a different overall track width between the front and rear lead to problems with the viscous coupling in the AWD? I know that different tire circumferences will... Thanks again!

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​​​​any problem with your PSM, you moved your size ratio from -1.6% to +2% ? Did you lowered your car by .5 inch or still stock ? I already have my 997 carrera wheels and trying to figure out what tires to buy (front is already on 235/35r19 potenza R050 i think) i dont have the budget for coil overs right now.

This should help you Charlie...

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That helps tremendously - is that tool available online somewhere? I see that with the stock sizes the scrub radius is 0. Should that by my goal when selecting spacers?

wheel-size.com. 0 or negative scrub should be the goal. I think if you get into the positive scrub category, you may find the wheel hits the fender well, but that's why they recommend a 30 series tire when using 19" wheels with the Porsche 996. Scrub radius is more concerned about the outer diameter of the tires causing problems with hitting suspension and fender well. But you don't want to use too thick of a spacer or the wheels will hit the fender's edge. That's why I suggested a mild 5mm to start, but you should be okay with dropping offset to 41mm using a 10mm spacer. If it where me, I'd go with 5mm.

Great, thanks again for all of the help! I found some old threads that confirmed the Sport Techno wheel option included a 17mm spacer for the rear. So now all of the numbers make more sense. I'm going to buy spacers to hit the stock offset as closely as possible. So it looks like either 5s or 8s for the front and rear. That should put me within 1mm the offset it should have had from the factory. I have 235/35 in the front and 295/30 in the rear. Just ordered 8mm spacers for all 4 wheels! Cheers Charlie

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My car was a 99 c2... no psm.