Ont924s

I am new to the 924 world having just purchased an 87 924S. I've only driven it about 600 miles so far and have enjoyed it. I'm looking to replace my 16 inch rims and just assumed I would stay with 16"ers. However today I was talking to a local Porsche 'expert' who says that in his opinion the car would perform better with 15 inch rims rather than 16's.

So I'd appreciate hearing from the more experienced and knowledgeable 924 drivers on this subject. Am I better off with 16 inch rims or 15, given equivalent tires on each? What are the advantages and disadvantages of each? I am not an overly aggressive driver but I do appreciate the cars ability to handle the corners.

Thanks

morghen

Perform at what? There is surely little to no difference between the two when you take into consideration how the car performs on the street.
With 15" it will look more oldschool...I currently have 15" wheels on my 924 and will swap for 16" wheels for looks.

Here is my 924 on staggered 15" phone dials.
I would keep the 16" wheels if you have them.

Holytin

To me the OP asked a clear question and the answer is "Moment of Inertia". 15" wheel has less of that given the smaller OD. And the 15" wheel is lighter. All that allows the vehicle to accelerate faster = better performance. I believe the difference is quite noticeable and I prefer to run the 15" on the car. Porsche had a reason to furnish these wheels rather than the 16" wheels. However, I do agree that the stance of the car with 16" is much better with the larger wheels and I do have a set of 16" Turbo wheels which looks fantastic. Mine is a 88 SE and do have a second set of the original 15" SE wheels should someone be interested. Cheers, Andre

Ont924s

Thanks for the responses. The local 'expert' I spoke to suggested that the front end components and suspension parts would wear out much quicker with 16 inch wheels. It didn't make sense to me as my owners manual notes 16 inch wheel alternative.

Here in Ontario we have something called a safety certificate. This requires that the car pass certain safety standards before it can be licensed and put on the road. When I bought the car the PO had to put new tires on it to pass this inspection. So I've got brand new 16 inch tires on the car now. They aren't the greatest tires but I'm still somewhat hesitant to go to 15 inch wheels and not use the current tires. I guess it will boil down to finding rims that will fit that I like and can afford whether they are 15's or 16's

morghen

Look, Porsche offered 16" wheels as optionals so the cars have been tested and approved with 16" wheels and since they publicly released the performance figures you can be certain that the car will perform the same with any of the optional equipment.

I really doubt you will feel or notice or even be able to measure any performance difference between 15" wheels and 16" wheels as long as you keep the same wheel diameter (lower profile tires on the 16" to keep the same diameter)
What you may feel is a stiffer sportier ride and a bit less "body roll" as the 16" tires will compress a bit less while cornering.

As seen in the pictures above I'm running 15" wheels on my 931 and its confy yet sporty to drive...but...a bit on the soft side when it comes to cornering capabilities. I compare it with my other 924 with 17" wheels which corners more crisp and precise due to less rubber to flop around during cornering.

Regarding wear...what the...? what experts are you talking to?
I'm not putting loads of miles on my cars but I do have them since more than 10 years...and no..nothing wears quicker with one inch bigger rims...don't be silly.

Holytin

Forgive me but you are so negative...

I'll try again. You say you "really doubt you feel or notice" a performance difference when installing smaller rims. I challenge you to really try! I'm not saying this without reason - the car will perform slightly better! Moment of inertia! I'm exercising this right now on a '88...

But you are correct of the stiffer ride or " body roll". The bigger rims improve the handling, which have a negative (slightly but it's there) impact on wear. The bigger the rim the greater the initial lateral forces on your suspension parts. Everything reacts much faster - that's what you feel and appreciate when taking the car into some sharp turns. The smaller rim has more rubber between the street and the OD of the rim - this rubber acts like a shock absorber. Less rubber less damping force and that's why you have slightly more wear on your suspension parts. And because a responsible driver knows all that (he is not a fool) he is not going try to push a car in a sharp turn with over 70 mph having 15" wheels installed. Of course, with the bigger wheels the car handles much better so now this is getting much more tempting ergo the car will be driven harder. Makes sense, doesn' t it...?

morghen

I had a rough day, I probably have been a bit negative. My apologies.

However, I may be insensible...I own a 924 since 2003, used 15" wheels on it, used 17" ones, I also own a 931 on 15" wheels. I converted two other cars from 15" wheels to 16" wheels and I really could not feel any difference except the car felt a bit more stiff due to less rubber to flex.

Regardind wear...I may be wrong or insensible again, but I have not seen any wear in my 17" wheels equipped 924 in the last 10 years or so.
I don't deny that there may be additional wear, I'm just thinking the additional wear is so small you wont notice it..just like the moment inertia...I know I cant notice it....actually wait I can...in my girl's 1.7L NA diesel with 50hp I can as I upgraded from 13" wheels to 15" wheels.

Holytin

See....

But I generally agree to what you said before. Performance differences as well as the wear factor are small but still.

Have a great day!