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Thread: Wheel help going from stock 16" to Z4 18"s

  1. #1
    Join Date
    Mar 2018
    Location
    South Carolina
    Posts
    26
    My Cars
    2002 z3 3.0

    Wheel help going from stock 16" to Z4 18"s

    So I have a 1.9 Z3 that I have slowly been bringing back from the dead. It was mothballed for years by the previous owner. One item on my hit list is wheels and tires. The tires I have are dry rotted and wheels are not my style and hashed on anyhow. I have a lead on some type 241 Z4 wheels in great condition with good tires. My questions are these....

    1. How bad will the ride become going from 16" to 18"? I live in an area with garbage roads. I know I don't want to ride around as though I have wheels made out of boulders like the Flinstone's. My father had a Probe GT years ago that had low profile tires that felt just that way. Some of it was likely the car itself, but I don't know. I've never ridden the same car with both wheel sizes. This car will never be tracked and is a daily. Thoughts on ride quality? I had 18's on an old Audi A4, but that was a totally different type of car.

    2. The lead I have is good for wheels and tires, but if I have to put spacers on the deal is no longer that great and might as wait for something different. They are staggared 8x18/8.5x18 and according to BMWStylewheels.com they have an offset of 47/50 respectively. Will they fit without rubbing on the suspension?

    3. It's a fair amount of metal being added in 18s vs 16s. I've read that can cause a penalty on performance. I don't know if I want to go too much less...lol. Any thoughts on the 1.9 and 18s?

    Thanks all for the info. I've searched and I haven't found exact answers to these questions. Any help would be greatly appreciated.

  2. #2
    Join Date
    May 2002
    Location
    SW Florida
    Posts
    12,681
    My Cars
    99-01 M Cpe & Rdts, X5M
    Your brakes will look puny behind the big wheels__the primary reason to have big wheels was to clear bigger brakes.

  3. #3
    Join Date
    Feb 2016
    Location
    tempe, az
    Posts
    2,695
    My Cars
    1998 Z3M, 2006 330i
    I wouldn't worry about the ride, unless you're planning on super low profile tires. In general, larger diameters ride better. You have to compare the 47/50 offsets to the stock wheels for your car. You can also get tire Diameters and widths and compare. Just do the math and decide. Randy is right about the brakes, but if you like the wheels, it may not matter to you. If you end up with a larger tire diameter, it could affect the performance, but again, you can calculate how much. I like large wheels, so I say go for it if they will fit. I put the 224 wheels on my 2.8 Z3 and it made a world of difference in looks. Here's an easy to use tire comparator: https://www.discounttire.com/learn/tire-size-calculator ... And heres' one with offsets: https://tiresize.com/wheel-offset-calculator/

  4. #4
    Join Date
    Oct 2017
    Location
    Estonia
    Posts
    1
    My Cars
    1996 BMW Z3 roadster
    1. Comfort
    When changing rim size, ideally you'd want the overall wheel diameter stay the same or as close to stock as possible for at least plausible speedo readings. This means that bigger rims have less rubber around them and that = more precise handling but harsher ride. Added bonus is hightened risk of wheel damage (you said the roads are garbage).

    2. Fitment
    Bigger wheels make a car look higher. Many have surprisingly found themselves looking for lowering springs or coil-overs after going up 2in or more in rim size to make the fender gap smaller. My very sloppy math suggests that for example with described ET the inner wall of new rear wheel would be little over 1 inch closer to strut than stock. I'm not sure but I think there might be enough room in wheel wells, I haven't looked around there that close.

    3. Weight.
    You will lose some acceleration and braking performance. As a fellow 1,9 owner I can say, you will definitely feel the difference in acceleration, and I myself only went from 16's to 17's.

  5. #5
    Join Date
    Jan 2015
    Location
    Japan
    Posts
    120
    My Cars
    Z3 2.2 Roadster
    I had Z4 17's on the car when I bought it, changed to 18" Advan racing. Outside diameter of wheel and tire should be the same as original. As for the weight? Depends on the wheel you choose. Mine were 3KG+ less per wheel. Ride is no different (17 to 18 inch)

    As for looks, you decide
    Attached Images Attached Images

  6. #6
    Join Date
    Sep 2016
    Location
    Yulee, FL
    Posts
    93
    My Cars
    2000 Z3
    I found some Z4M wheels for an irresistible price and went with it. The front tires that came on the wheels rubbed the front struts, so I bought fronts and rears (Conti ECs) that were equivalent in height to what came on my car. The ride is a bit sharper, but the car handles better, for what it is. Under very hard turning (circular off-ramps) the rears will rub on the outer edge of the fender liners a little. The brakes do look really small with these wheels, but I am under no illusions that I am driving a race car, a hypercar, or that I do anything that would require larger brakes. It is just a fun weekend drive car and I wanted it to look a bit better.


    1 20180420_102239.jpg

    Stubbornness is a virtue....

  7. #7
    Join Date
    Mar 2018
    Location
    South Carolina
    Posts
    26
    My Cars
    2002 z3 3.0
    Thanks everyone. Great info. I am waiting for him to get me the DOT info to find out how old the tires are. I keep going back and forth, because they are still not my #1 choice. But the deal is almost too good to pass up.

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