[BeBe]

At some point in the life of my car, the owner put 18" millie cup (911) rims on. I understand wanting a larger contact patch, but I was curious what the other pros/cons are. The tires come right out to the edge of the wheel wells (or maybe a bit further). I don't know if that is just because the rims are wider, or if the offset is different. In general, are these rims a desirable change?

Partial Post: Please Login or Register to read the full post.

[94SilverCab]

18" wheels are not recommended by Porsche. Many people who have run them have reduced to 17".



YMMV,



Jay

Partial Post: Please Login or Register to read the full post.

[flash]

there are definitely pros and cons.



they can look very cool, and fill up the wheel well nicely. the cornering can also improve if the setup is right.



as stated, they are not recommended by porsche. they generated a memo a while back recommending against it.



this is because the added stresses they put on the suspension components is beyond design tolerance, and results in premature wear and/or failure.



the added weight that most of them add is also detrimental to both acceleration and braking.



depending on the offset, width, tire choice, etc, the handling can actually degrade too. many times the result is a tendency to wander and tramline.



harsh ride is the common complaint though, and the primary reason that many go back to 17s.



i have 18s on my blue car. with tires it came to over $8k. i went out of my way to have them made to fit exactly as i wanted, and fit the tires that i wanted. that being said, they are still heavier than i would like (and i chose a very light rim and tire). if i had it to do over again, i would have gone with 17s, and still might. i have 17s on the white car and the ride is much more compliant. i would give up some cornering, but the ride quality would improve.



i hope that helps

Partial Post: Please Login or Register to read the full post.

[robadams56]

I haven't done the math, but most cars I see with the 18's seem to have picked up a little ride height in the process. I suspect that at some point you can't trade off enough sidewall to wheel height to keep from picking up overall height. I wouldn't mind having a set of two or three piece wheels with the proper offset to fill up the wheel well but I don't know if they are available in 17's. Seems like most manufacturers use 18" as a starting point these days.

Partial Post: Please Login or Register to read the full post.

[flash]

that isn't the case on my car. i was able to retain the 25" outside diameter. i have 285-30 on the rear and 255-35 on the front



i went with the 18 because i wanted the reverse offset rim, and they didn't do it in a 17, so my case is a perfect example of your point.



tire choices are slimmer in 17s too

Partial Post: Please Login or Register to read the full post.

[robadams56]

The wheels on your 968 look great and you're right....they don't seem to have raised your overall height. That's good to know.

Partial Post: Please Login or Register to read the full post.

[BeBe]

Tramlining with the current setup is very prominent. What is the "proper" offset (or range) for the 968?

Partial Post: Please Login or Register to read the full post.

[flash]

it really depends on the rim width, tire choice, and alignment settings.



it also depends a LOT on the wheel and tire weight. heavier wheels and tires will tramline more than lighter ones (pretty basic physics there)



a lot of people put wheels on the car because they look cool, but fail to take into account the weight and its effect.



also, tires generally weigh more than the rim, so that is a major factor, and should play into any tire choice at least as much as price.



block tread patterns tramline more than smoother more sweeping patterns too.

Partial Post: Please Login or Register to read the full post.

[ron1688]

Hey Flash, can you tell me how many pounds your 18" wheels weight? Im also considering getting 18" on my car. I was looking at the Victor Insbruck or Tursimo from Wheel Dynamics. I was told that they weigh 18lbs and 19.5lbs. Also, what tires are you running.

Partial Post: Please Login or Register to read the full post.

[Darth Vadar]

Best advice I can offer... drive your 968 with 16" stock wheel and tire combo, for at least 50 miles... note how light and quick it feels... how it goes where you even think of pointing it... how it really, really seems like an ideal sporting car....



Now... immediatley bolt on a set of 18" anythings with appropriate tires, and drive the same 50 miles... the feeling will absolutely knock you out! Clunky is the only word i can put to it... the car feels heavy, non responsive and generally NOT a sports car!!!



The 17" wheels are also a compromise, but if you pick something in the 18 to 24 lbs range, with any decent modern tire, you will balance the "heavyness" with the better handling and response... not perfect, but even Porsche agrees that 225/40x17's and 255/35x17's will cut the mustard... bigger than that and you are just posing....not really driving the car...



Just do it, and you will see what the diff really is!!!

Partial Post: Please Login or Register to read the full post.

[flash]

darth - good test. it would really show the difference. i recommend weighing them too, to show how much of a change there is.



ron - my front rim (9" wide) is 20 lbs and my rear (10" wide) is 22.5. my current tires are only 24 and 26, compared to the 28 and 30 of the previous S0-3s i had on there in the same 255-35 and 285-30

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

Darth,



It depends on the application. I've never been a proponent of huge wheels (and to someone like me who remembers 15" as being large, 18" qualifies as huge), and for a street car, I agree that a 16" or at most 17" wheel is probably the best choice for most people. However, I've spoken to several very successful 944/968 racers, and they all emphatically stated that 18" wheels are the fastest way around the track, hands down, because of the availability of wider tires in the larger rim diameters. But of course these guys are using ultra-lightweight, racing-spec (meaning very pricey) wheels.

Partial Post: Please Login or Register to read the full post.

[DaveN]

There is also a dearth of lightweight 17" wheels out there for the consumer; maybe ok for the racer? That's why I am going to 18" because I actually get a bit of a choice for light rims. These rims are substantially lighter than my 17" stock C2's so even if the tires are bigger I should loose some unsprung weight.

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

Dave,



Yes, I've noticed the same thing. I bought Pablo Crespo's 18 x 8.5 Enkei NT03-M's for the front. They're 19 pounds and change, which are lighter than any 17" wheels I could find when I was comparing. Now I just need to find a matching pair of 18 x 10's for the back...

Partial Post: Please Login or Register to read the full post.

[Dimma]

[quote name='94SilverCab' timestamp='1323135976' post='118840']

18" wheels are not recommended by Porsche. [/quote]

That's strange, since Porsche themselves mounted 18" speedline on the Turbo S ....

Partial Post: Please Login or Register to read the full post.

[flash]

perhaps, but it's true. there is even a memo about it.

Partial Post: Please Login or Register to read the full post.

[polliviere]

I for one have done the 16" to 18" test and was shocked at how the car responded. I purchased a set of Sport design wheels with pilot Sport tires, 18 x 8 and 18 x 10. The tires were 225/40 and 285/30. When i replaced my stock 16" C2 Turbo (C2 Turbo (Cup 1))'s the first thing i noticed was the increase in ride hight, but the shock came when i drove the car. Tramlining was just the begining, the car felt like it had gained a ton of wieght, it was slower and handled like I was driving in thick mud. I put up with this for days before the 16" wheels went back on.



To make a long story short, i sold the set on eBay for what i paid for them and found a set of 17" twist to replace them. I had the same wheels on my previous Cab and was very pleased with the ride and handling so i went back o what i knew would work.As a final bit of luck i only paid $325 for the 17" wheels and tires. When i shipped the 18" wheels and tires to the new owner i checked the wieght, the fronts came in at 47lbs and the rears a 57lbs.



Peter

Partial Post: Please Login or Register to read the full post.

[ron1688]

With my current 17" set up, the front weights in at 43# and the rear weights in at 50.5#. If I were to go with the 18" Victors Insbruck with Nitto NT05, the front would weight in at 40.75# and the rear would weight 48#.

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

Shouldn't it stand to reason that if you can find a set of larger (e.g. 18") wheels that weigh about the same as a smaller set (due to the use of better alloys, and more advanced manufacturing methods) that the overall weight of the wheel/tire combination should then be less, given the same total overall outer tire diameter, because the tire's sidewall height is going to be less? And further, by having a slightly smaller proportion of the overall weight be near the outer periphery, shouldn't this make for a slightly more responsive car?



I realize this is a hypothetical, because generally within a given wheel brand and price point, a larger diameter wheel is going to weigh more than a smaller one. But my new 18" Enkei's feel light as a feather. And for the record, I went ahead and bought a set of heavy duty A-Arms with the larger diameter ball joint pins from Racers Edge.

Partial Post: Please Login or Register to read the full post.

[tamathumper]

I don't know if this is part of the reasoning or not, but it seems to me that given two wheels of the same overall weight, one being 16" and one being 18", the "rim" (and all of its weight) of the 18" is going to be further from the centerpoint, and therefore should require relatively more force to get moving or to stop.

Partial Post: Please Login or Register to read the full post.