calculating wheel ET
 

Hi all,

The car in question here is an early offset 84 944 with 7X15 cookies and 225/50/15 tires, lowered 1" all around.

With the current poor choice of good 15" tires, I'm looking at "upgrading" to 17" wheels. And Oh Boy, I'm confused. I've searched here and other forums and I'm no better off. Before I get into offset questions, the first one is - With extra width wheels (9" instead of stock 7"), where do you want the extra 2 inches to go, 1 inch towards the outside and 1 inch towards the frame, or all towards the frame? Clearly, all towards the outside (body) would cause fender lip interference. Knowing that, how do I then calculate the offset (ET?) of the new wheel? I'm looking at new wheels and I want to avoid spacers if I can (other than the stock rear ones currently on the car). It doesn't make sense to buy new wheels, then add spacers. I won't be going crazy on tire sizes, 235-245 max. Can anyone help me out here?

Thanks as always,
Gord.

It took me a month to get my head around offsets and how it works on my car. This site explains it pretty well. The problem you will run into is wheels are only made in a few offsets usually. You may need spacers just because what you want isn't advailable.. now if you want custom offsetts get out your check book $$$$

https://www.rsracing.com/tech-wheel.html

Hi Gord, I just went through the same thing you are now going through. There are after market wheels with the same early off set made in Italy. I found that the people that have the early offset, newer type 17" wheels think they are gold plated what with the price they are asking for them. I did not want to use spacers either, but ended up doing so with Porsche Turbo Twists 17 X 7 ET55 with 205 X 50 X 17 in front and 17 X 8.5 ET50 with 255 X 40 X 17 in the rear with almost new Michelin Pilot Sport PS2 Tires. The whole set up with shipping came to $730.00. I could not pass up that kind of deal. When my wheels arrived I inspected them and only found a 1" mark on one rim edge from a tire mounting tool. I have the front spacers and am now looking for the rear spacers 1.5 inches thick. Look on EBay for Porsche Wheels and you will find out what the wheels are selling for and their condition. Ask questions if you find ones you like and look at the Sellers rating up at the top. Take your time and you will find a good deal.

Best of luck,
Larry

You can also consult WheelEnhancement.com. . .a great source of information and good condition takeoffs.

On my 85.5 I put 17 x 8's in front with 245/45-17 Goodyear, and on the rear I put 17 x 10's with 275/40-17 Goodyear. On the rear I wound up using 12mm spacers to keep a better clearance space on the inside of the wide tires. There is surprisingly allot of room under the wheel wells of our 944's I have found. The offsets for all of the rims were the early dimensions for 83 to 86 944's, which is what I have.