18 or 19 Inch Wheels?

OK, everyone. I've done a pretty extensive search on the 996 forum and found several (dated) threads of the benefits and drawbacks of 19 inch wheels on the 996. The serious topics on the issue were in and around 2005/6. Most of the "problems" centered around: 1/ Wheel weight, 2/ Clearance, 3/ 19" tires available. Since then, there has been tremendous interest in 19" and greater wheel diameters. And there seems to be a larger selection of tires/rubber compounds. We all know that 19's are standard on 997's... My questions are: 1. Are there any technical reasons for not moving to the 19" wheel? 2. What are the recommended sizes (without spacers)? Is there anything special I need to pay attention with regard to offsets? I currently run 295/30/18 on the rear and 225/40/18 on the front. 3. Is there a difference in performance? I know that when I recently increased wheel size on my Jeep from 15's to 19's, the gearing ratios were completely out of whack! 4. What else am I missing? BTW, I currently have the HRE C95's (will keep for cross and track events) and am thinking of going with the HRE P40's. Comments?

pics of the jeep

Will post Jeep pics tomorrow. Its an '03 (I must like that model year!) TJ Sport w/ 3" Skyjacker full suspension lift, 19" ProComp Rims (cheap), and Mickey Thompson Tires (not cheap!). I love it, but, am thinking of selling

Here's what I've found/heard, since I've been doing some research into 19" wheels and tires: 1. Rougher ride with the 19's; I've been told that 19's may cause issues with the AWD system (I'm not sure I believe this though). 2. On a C4S, you'd want to go with 235/35/19's in front and 305/30/19's or 315/25/19's in the back. You'd want to stick to wheels that are about 8.5" in front and 11" in the rear. If you are looking at HRE's, they should be able to supply the correct offset wheels for your WB C4S. 3. More grip due to a wider contact patch! Not sure what happened to your Jeep - maybe someone more knowledgeable can answer! 4. Cost of the 19" tires!!! :-D Hope that helps!

I dont know the real reason... but my PSM kicked on sooner when I had 19" on... I def can push it more with 18" (and this is spirited street driving). Im thinking for the rears it is 19/12 you can go gt2 spec should be max.

[QUOTE=ATL Fahrer;7324613] 1. Are there any technical reasons for not moving to the 19" wheel? QUOTE] ATL, in your search you may have seen posts saying that the 996 suspension wasn't designed for 19" and that it stresses the suspension (and could also possibly damage it). I recall one which even claimed Porsche tried 19" on the 996 suspension and modified it for the 997 because it didn't work. Some would obviously debate this but it's out there...

I have stock 17" wheels. That said, I think 18" would be my choice rather than 19"s.

seen 19's on MKI - looks wrong to me but a GT2 wing looks right?

I don't know, the 19's on this TT look pretty good to me!

P40's....end of story...

Agreed, so same look for you as the turbo pictured, minus vents in front of rear wheels. I guess I'd prefer 18" especially if there is a weight or handling penalty.

19s on my 04'. I like the look at least. My wheels are deeper however. I am always on pothole patrol!

I haven't followed the performance wheel/tire sizing for auto over the last few years but in motorcycles 17" diameter f and r has pretty much been optimal for the ultra high performance street, superbike racing and GP. This has been pretty much the standard since about the last 20 years. The widths, 3" front and 6" rear hasn't changed either. I do know that 18" auto wheels were the highest performance standard for several years and until quite recently when the diameters were growing by an inch or two a year and everything from Hummers to Escalades had huge diameter heavy shiny chrome wheels with extremely low profile tires. The bling factor carried over to exotics and Euro performance cars. I like chrome on my Harleys but not my Porsches. I still think the lighter 18" wheels with less rotational mass would be as good as anything and better than most. The 18" tires are comparatively less expensive now as they are less of a novelty. I'm very happy with my 18" on the Carrera and even the 17" on the wifes Boxster. Even if I purchaed new wheels, I'd stick with these sizes.

hard to argue with that ^^^^^^^^^^^^^

I just had a epiphany. If you want more performance 18". If you want more people to look at you 19". You are the master of your destiny. Although more people looking and a minuscule less performance sounds right in the hedonistic world we live in. That's my skewed opinion. Did I help?

Another thing to consider is the car really should be lowered at least a bit w/ 19's, to avoid looking "jacked up" and emphasizing the fender gaps. So in my book, if going to 19's you need to factor in the cost of new springs (and make sure they match well to the stock shocks, unless you swap it all for coilovers). Hey, anything I can do to help you spend your money on mods, I'm right here ...

From any rational performance/engineering perspective, 18's are better than 19's. Note that all the highest performing 996s from the factory had 18's (GT2, GT3, Turbo S, etc). The 19's are just for bling unless you are driving a 997 (which was redesigned specifically to work with 19's).

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I've heard this quite a few times but I don't understand what "redesigned specifically to work with 19's" means! Assuming that the 19's don't incur a weight penalty compared to the 18's (i.e. the weight of the 18's and 19's is roughly the same), what would the issue be?

Thinner sidewall maybe? More of the rotating mass further from the hub? I've wondered the same thing, actually.

I'm running 19" turbo wheels and no spacers. Car came set up this way. I don't think it rides rough. 235/35 front and rear 275/30. When it needs tires I'm going to 295/30's in the rear next time. No problem with tracking just want more rubber back there.

I just got a set of Carrera 18" wheels (the car has 17" now) that I bought on Ebay. They are off a '08 and can't wait to get them on. I decided that there was too much bling for me associated with aftermarket wheels, especially 19", and that the BBS were the most appealing. I was afraid of aftermarket quality. I also live on dirt roads where potholes abound. I can't believe the price of center caps. Anybody got any around with the Porsche crest (colored) that they are not using?

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I agree, NB 996 here and no probs with 19's and the ride is not rough. Pac996, are your rears 19 X 11 ? I would say definitely step up to 295/30's. the 275/30's were almost identical to the 255/40/17 OEM tire heigth; ( 25.49 vs 25.03), so I initially went that route. but they looked terrible on a 19 X 11 rear wheel. 295's are 0.93 inches taller than OEM 17's, which equates to a 2.2 mph difference on the speedo. But they look a heck of alot nicer on the 11inch wide rim. I vote for 19's. rotating mass be damned ...upgrade the brakes...

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I think this is it. And more critical is tire mass further from the center of hub. The rotating mass as it is moved further from center stresses all the suspension components to a greater degree. These components further work the chassis or unibody at and beyond their points of attachment. For this reason on early Boxsters, '97 and '98, I believe, the factory warned adamantly against fitting 18" wheels. In '99 and beyond the Chassis was stiffened to handle the added stresses incurred with the 18" wheels.

Makes sense.

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If the total diameter of the wheels & tires are kept the same between 18" and 19" (and you usually do this to keep the speedo accurate), does a minor redistribution of weight along the radius really affect it that much? On previous cars, I've run +1 wheel and tire combos that were significantly lighter than the stock combo. If this is the case, is there still an issue?

19's will work on a street-driven 996 obviously, as many here can attest. It's just that the chassis and all the suspension parts were designed to work with 18's, so I believe (and I think this is the majority consensus) that 18's will work even better (again just speaking from a performance/engineering perspective). Slap on a set of quality 19's and your car will still function, especially if they are light & strong. But I suspect factory engineers prefer to keep things conservatively within their own design parameters, and 19's with their lower profile tires (to maintain the same total OD) will necessarily have less sidewall flex, less lateral deflection and less bump compliance than 18's and will therefore trasmit greater forces to the suspension parts and attachment points than 18's. Tootling around town this makes no difference, but if you are operating at the limits of the vehicle, the forces involved *may* come close to exceeding (or surpass) the intended design thresholds of the stock suspension components. I don't know what the weakest link is, but there are forces acting on all the suspension bushings, the eccentric bolts used to align the car, etc, all of which have specs intended to cope with the softer 18" wheel&tire combo. Full disclosure, I am not an engineer. But annecdotally, in 10 years of attending PCA track events I cannot recall ever seeing a 996 running 19" wheels on the track. Maybe there is a reason.

I think there is a reason why mostly all Porsche wheels are flushed to the hub (minimal lip), most of the stress going around the corner is directly distributed to the hub, while wheels with a lip puts stress on more on the lip instead of the hub.... I believe this and the lower sidewall is the reason why the 19" setup I mounted was very jumpy and lowered my PSM threshold... they do look cool but, after awhile, you want performance back. renn-a4.jpg

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It's a difficult question to answer, being that we are speaking in general rather than specific terms. Weight wise, how much is "minor"? And, how much is "that much"? To answer your questioin another way, If looks trump everything else, and you favor the 19s, go with them. If optimum handling, responsiveness, braking, accelerating and agility are more important than bling, I'd choose the 18" Now, probably the difference on the street would be quite subtile to most all except those most in tune to what's going on. To an experienced driver that tracks his car at or near the limits, the differences may become quite or even very apparent. To maximize performance, often weights are measured in grams and lengths in thousanths or millimeters. Hope this helped.

18s for the track. 19s for the street. I've read here from searching that wheel bearings go bad on stock wheels, stock setups... since there are less folks running aftermarket, haven't come up with very many 19" issues just from running 19s. No scientific studies done so pretty much just like anything else on the internet, go do so at your own risk.

1. Are there any technical reasons for not moving to the 19" wheel? Yes, your shocks are set for the extra padding of 18" tires and the weight of cast wheels. But, you can keep the same aspect ratio by increasing the tire diameter, or you can get new shocks and much lighter wheels. 2. What are the recommended sizes (without spacers)? Is there anything special I need to pay attention with regard to offsets? I currently run 295/30/18 on the rear and 225/40/18 on the front. Best C4S sizes: 18" 335/30ZR18 on 12x18ET45 rear, 245/40ZR18 on 8.5x18ET40 front (GT2 wheels with oversized tires) 19" 325/30ZR19 on 11.5x19ET44 rear, 255/35ZR19 on 9x19ET53 front (requires PSS10 or similar suspension) I have run both of these on a C4S with no rubbing using Pilot Sport PS2 tires and minor rubbing in front using R-888 Proxies. 3. Is there a difference in performance? I know that when I recently increased wheel size on my Jeep from 15's to 19's, the gearing ratios were completely out of whack! Be very careful here, more than 3% offset in front-to-rear diameters will confuse both PASM and ABS. You don't want these systems confused on the track! 4. What else am I missing? 19" wheels provide sharper turn-in. Lighter wheels provide smooth, agile control. 18" tires are more forgiving. Light 19" wheels and tires with a good racing suspension will make your car smoother than heavy 18" wheels with a stock suspension. Avoid two and three piece wheels, they can leak. The lightest (non-carbon-fiber) wheels are Champion RG5 (21 pounds rear, 17 pounds front) Stay away from run flats! they're about 6 pounds heavier.

Thanks, everyone for the insightful commentary. I certainly have a lot to think about. The really good thing is that I do have a set of 18's, so, I may be able keep them for any track work that I may do and get the 19's for the street. Decisions, decisions... Maybe I should start another thread looking at performance mods?!?!

Performance is easy, Bilstein PSS10 for corners, VFE supercharger to go faster, Gyro slotted two piece rotors to stop faster. Remember to upgrade to Motul or Super Blue after modifyong the brakes (you don't want to learn about boiled fluid approcahing a corner at 130 MPH).

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It's even easier than that! Slap a few "Type R" stickers and that should be good for 20hp per sticker!

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Looking for performance mods? Easy, first scrap the 19" wheels and tires... LOL

I say 19's (unless you're going to be driving the car at it's limits). As for tires, go with 245/30 in front and 315/25 in the rear. Add some coil-overs and I guarantee that it will look sensational! https://rennlist.com/forums/996-foru...oto-shoot.html

its pretty obvious!17 inch or 18 inch,thats the way it comes,that is all!

Not trying to start a firestorm here, but, I find a lot of the comments interesting. Much is mentioned about how the Porsche design engineers have set the car to PERFECTION, yet, many make certain mod's that they deem necessary - performance being the biggest area. IF the car comes as intended from the factory, why does Porsche have a list of "hundreds" of options when you order the car? In speaking w/ the dealer, they often mention that the option list is so long b/c they want to give the owner the opportunity to make each car unique. I'm not saying I know everything (far from it!!!), but, is it possible that the factory did not include 19's as an option b/c the technology and tire combos did not exist that Porsche felt comfortable with up to 2005? You have to admit, before 2005, there were not a lot of street cars in any category running around with wheel diameters greater than 18! In speaking with some of my friends that track cars extensively, they have stated that the most noticeable difference on the track is a slight loss of power on exiting turns. BUT, due to more rubber contact - 315's vs 295's, there is a slight gain in grip, which could be negated by less flex due to tire wall height! I guess there is no right answer. I have to say, though, the opinions are very helpful.

For bling factor, 19's are just the start. 20's are common on almost any "sports" car. Camaro's, Vettes, Vipers, NSX's, etc. If any car is to get DE'd, AX'd or tracked..then weight and wallet content become part of the equation. On larger sedans.. it's a matter of choice...Cadillac, Lexus, Infiniti, Acura, 7 series BMW's are riding on 22's. Forget SUV's, 22's and up.

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I don't believe that 19's will be better or equal on the track...you need a softer tire compound and taller sidewalls which are the more important advantages of 18's on the track. I'd keep the 18's for the track and do the P40 (Brushed) for the street...widebody begs for lowered on 19's for the proper street look.

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... and that would be?????

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see examples below... BmTI2swBmkKGrHqYH-DEtFg13Q-GBLfLcd0.jpg side.jpg n408445329005697535pv6.jpg PIC-0032.jpg

FLY996 from your avatar I see that your wheels are set up nice & tight. But not the case w/ a couple of the other examples you posted. Once the top of the tires begin to disappear into the wheel well, it turns the car into a caricature of itself & looks goofy IMO. But to each their own...

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Agree 100%! I'm a purist and I wouldn't hesitate to run 19's on the street. 17" will not fit on a C4S due to brake set-up.

Very interesting comments on this video. Note that what the driver says does not match the results. I know that the test is done on Japanese cars by Japanese drivers, but, I would say valid nonetheless. http://www.youtube.com/watch?v=o6Glkf4jwkM

Outstanding contribution to the discussion ATL! You have my vote for post of the week.

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Not really valid when you consider they used a staggered setup on the 19" test vs. a poor setup on 18's.

Good video FLY very informative.

For anyone leaning towards the 19 inch route, we have the recommended tire sizes (235/35/19 fr and 315/25/19 rear) in stock again from a few different manufacturers. Shoot John an email if you're interested at [email removed] .

I thought the video was interesting. In particular, all the changes to the body structure and suspension that were necessary to put 19" wheels on a production car. It really shows how much more stress goes through the suspension with the larger wheels and tires. There's more to it than "will it fit without rubing" or "it's okay if the rolling diameter is close to the stock setup". Personally, I plan to stick with 18" wheels when I upgrade mine.

I always preferred 19's IMG_3154.jpg

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I have the Turbo 18" wheels and to be honest, having to run with 44psi makes the ride very harsh as far as I'm concerned. Can't imagine what running with 19" whels would be like with the even narrower side wall section. I'm even considering going to the 17" wheels, which run at 36psi I believe.

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Not sure I undertsand that......given that an ojective when fitting larger wheels is to keep the overall diameter of the tire the same as stock (for speedo and on-board electronics etc, there's no change in effective gearing so why the perceived change in exit power??

If anyone is out there please help answer I have a set of wheels 18" from a cayenne twin turbo will those. Wheels fit on a 1999 carrera 996 ? What has to happen if they will and the width of the tire is it a concern. I have an all season 20" summer wheels on the 04 955tt so I don't take off and put the 18" with snow tires any longer so I have 4 really nice wheels with the badging on it plus they look cool and I believe there's no road rash /rage on them please some read this last post was 5 years ago "

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Post pictures of the wheel including a closeup of the value stem. Porsche prints the wheel offset at that location. That will determine if there's a chance to work with the 996 without scrubbing and other issues. Also, if these are OEM Porsche wheels, they'll have a part number on the inside.

I have 19" TechArt wheels on mine. The rear I think works out well and looks fantastic. On hard turns the fronts actually rub. Not terribly but I'd probably do a slick set of 18's.

great read. posting to subscribe as i start my trek towards more-than-likely going with 19s.

So for my 996, I am kind of a purist and like the look of the 18s and will likely stick them for my car. They just seem to look right. I have put on wheels from my 997 just to try them but they seem to be too big. I think the only way if would work is if I used a lower aspect ratio tire (for the rears going from 30 to 25. Then it could work. Also, unless you lower or have some aero modifications the 19s make the car look like a jelly bean on wheels. My point is, if you go to 19s, you need to change a few other things to make it seem integrated. Again this is just my opinion and I always urge folks to do what makes them happy.

I chose to go with 19's only because I found a great set of Kinesis F110's for sale that I really liked. The wheel and tire sizes are Front 8.5 x 19 w ET50 235/35/19, Rear 11 x 19 w ET64 295/30/19. Tires are Bridgstone S-04 and I do not feel any ride difference other than less roll. The wheels are approx 4 lbs less weight each (and much stronger) with Titanium Lugs (saving another .4 lbs per wheel). I do not track so cannot offer any opinions on that. Not an expert in any way but my new tire set-up is much lighter so do not understand the additional stress on suspension. I do plan on installing the ROW M030 in the near future.

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I hear what you're saying and i agree with you. Last month I put 37 inch tires on my truck. Of course, I couldn't just put tires on my stock wheels. I had to get the right wheels too. Then, I had to lift it to clear the 37's,so, I had to get suspension work done. Of course, I had to get all the upgrades and accessories for the lift. Then, the stock fender flares arent wide enough to protect the paint with the new wheels (due to the negative offset) so i had to order new fender flares. Of course, the fender flares had to "match" the wheels I got. It has to look right. Of course, now that the truck is lifted and on 37's, I couldn't have just regular nerf bars along the side of the truck, it takes away from the lift. So, of course, I had to get the power steps. I mean, it has to all look right when it's all together right? I know exactly what you're saying and I'm kinda OCD like that too. :-) I have the aero side skirts. If I went with 19's, I'd have to at least drop it a little. I really like this kind of look: I love the way this looks. I may need a front bumper. D'oh. :-) I need to lower mine a little so the 19's have that aggressive look. I don't drive very aggressively other than some spirited highway left lane traveling every now and then, but, even then it's in short bursts.

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That C4S looks perfect....I agree with you...Right aero features and perfect ride height for the 19s.