Wanting to go from oem 17'' run flat to 19'' rim

[yrkprojects@gmail.com]

Hi there guys I'm new to the forum, please advise if going from 17" oem to 19" after market rim is advisable and if I do, will going non run flat give me a softer ride that I'm currently experiencing with the 17" rim? What are the pro and cons? Also will the car gain any height going to a 19"? Please advise

[Marcoose]

A 19”, even on non-RF, will be incredibly harder than a 17”. Noisier too.

Mind the offset to avoid rubbing the wing.

[yrkprojects@gmail.com]

Originally Posted by Marcoose

A 19”, even on non-RF, will be incredibly harder than a 17”. Noisier too.

Mind the offset to avoid rubbing the wing.

Ok so any advise to what I could do or is best to leave as is?

[Marcoose]

The first advice on going from RF to non-RF is buy a tyre fix kit and a pump. I have 2 motorbike kits, one for small round punctures, another for weird shapes. Knock on wood, I’ve only used it once on a friend’s motorbike. With that advice is a roadside assistance. I’m in America, I have AMA. You WILL get stranded. I had to get towed 2 weeks ago. The puncture was unrepairable.

The second thing is offset. I don’t know the OEM offsets. There’s a bloke on the U.K. forum that knows all this inside out. If you don’t want to be bothered with all that, then buy OEM 19” wheels. Obviously they’re more expensive. But you know they work. Wrong offsets will ruin your project.

Thirdly is the rubber itself. I like perfomance and willing to overlook some increase in NVH. I’ve been very happy with PS4S. I bought them at America’s Tires. (The road hazard insurance is worth every penny!) I'm using stock sizes, and I reckon I can go one ratio up next time.

Let me know if I can be of further assistance. Glad to help.

[surfwooder]

From your post you seem to be looking for a softer ride by buying 19" rims vs stock 17" rims. This will not happen. The larger rims will only reduce the amount of sidewall on your new tires, thus making any hard hits on pothole even more devistating to your tires, and suspension system. You will not change the actual diameter of your wheels. If you think you'll 2 more inches to the height of you Z, wrong. You'll reduce the amount of side wall to absorb the bumps. Take a look at these wheels on the model on the Tire Rack site. As someone mentioned earlier, just remove the RFT, and install 17" standard sidewall tires. You'll get the softer ride you're looking for. I've had that very same result when I removed the RFT from my 2008 328IC, and bought NRF. I got better, softer ride, and better handling. My Z came with RFT and they are gone when tire time comes around, probably in the Spring.

[Medicman1972]

Hi guys, newbie here. Found the thread really helpful. Could I just confirm that when changing standard 19” (Z4 3.5IS) RFT for standard ones of the same size, I don’t have to change the rims? Heard that RFT. have to be on special rims.
Thanks in advance.

[KennyP]

Originally Posted by Medicman1972

Hi guys, newbie here. Found the thread really helpful. Could I just confirm that when changing standard 19” (Z4 3.5IS) RFT for standard ones of the same size, I don’t have to change the rims? Heard that RFT. have to be on special rims.
Thanks in advance.

There arent any special RFT rims on Z4. You can fit any tire you wish. Michelin non-RFT PS4S is a great option. Adds some comfort, handles better and if you think they are expensive then i have to say from experience with Supersport tire, that preceded PS4S, they last suprisingly long aswell.

[Marcoose]

Medic, what Kenny said. Just plug and play. I reckon you can go one ratio up for added comfort. But I’m not positive.

[proboner]

If you want to stick with stock sizes you're looking at 225/35/19 front and 255/30/19 rear. This will certainly be quite a bit harsher than 17s, but switching from a runflat to a regular tire will help. PS4S is a great choice. As mentioned above, you can also try running a taller tire to keep some comfort and go with a 225/40/19 front and 255/35/19 rear. This will add basically a full inch to your overall wheel/tire package and won't be too big an issue, depending on your suspension and offset. I'd actually suggest taking a middle ground approach and keep the stock aspect ratio but go with something wider, which necessarily equates to a taller tire as well. 235/35/19 or 245/35/19 front and 265/30/19 or 275/30/19 rear. That's only about 0.6 inches taller than stock.

Then you need to make sure you're getting the correct wheels as well. I'd probably stick with 8.5" width with +25 offset (+- 5) in the front and 9.5" width with +30 offset (+-5) in the rear.

[Marcoose]

Wider and same ratio, versus same width with bigger ratio is sound as well. FYI, the 265 would be 1/4” taller. No problem whatsoever with wing clearances. You can fit the 265 and the 275 on the stock 19” rim.