Looking into getting a Z4

[Steve Jarvis]

Originally Posted by B21

I assume you have your wheels reversed..in any form 245/35 19 on the front is about as wide as you can go for many reasons unless it’s a garage queen..

I've already run a 255/40R18 on an 18x8 +38 offset on the front with no issues and a 275/30R19 (RT660) on an 18x9.5" +45 offset on the rear with no issues. Keep in mind that my son has an E46 M3 and runs 285/30R19's on 19x10" wheels with no rubbing. These 275 RT660's rub on the inside and outside on his car. Basically they're much wider at the shoulder of the tire than a 285.

I now need to measure my clearance (if any) with the above setup to see if any more will fit. You can go wider, if you don't go taller. A 245/35R19 is 25.75" tall and a 265/30R19 is only 25.26" tall. Stock is 25.09" tall. Stock bump stops don't compensate for a taller tire going higher into the fender well. On the rear, I believe a 285 is no issue but I have my doubts about the 19x10.5" wheel.

[B21]

Originally Posted by Steve Jarvis

I've already run a 255/40R18 on an 18x8 +38 offset on the front with no issues and a 275/30R19 (RT660) on an 18x9.5" +45 offset on the rear with no issues. Keep in mind that my son has an E46 M3 and runs 285/30R19's on 19x10" wheels with no rubbing. These 275 RT660's rub on the inside and outside on his car. Basically they're much wider at the shoulder of the tire than a 285.

I now need to measure my clearance (if any) with the above setup to see if any more will fit. You can go wider, if you don't go taller. A 245/35R19 is 25.75" tall and a 265/30R19 is only 25.26" tall. Stock is 25.09" tall. Stock bump stops don't compensate for a taller tire going higher into the fender well. On the rear, I believe a 285 is no issue but I have my doubts about the 19x10.5" wheel.

My references were to steering feel and tendency to white line..

I run 235 or 245 35 19s front and 275 30 19 rear..

I find the 245 is heavier on the steering and tends to find white lines (grooves in the road) more so..

Obviously running 18" front and 19" rear is a new ball game

Sitting nose up seems counter intutive?

A 255/40 18 tyre on an 8" rim seems to be lacking adequate support too? Most guidance would suggest that on an 8" rim 225 is the correct size a 255 /40 in 18" would require a 9" rim..?

[Steve Jarvis]

I was only testing the 18" front 19" rear for clearance. I moved the current rear wheels to the front and mounted my sons autocross 19" in the rear, to do a test drive and see if they would rub. It will be 19" front and rear.

I have run as wide as a 285 on the front of my cars and I have found that the tire design has a bigger impact on a tire following grooves than the tire size. The alignment is also a factor as well as trying to decide the impact on the Z4's electric steering. Of course the roads in my part of the US may differ from your roads.

My front will be a minimum of a 255 on an 8.5" and the rear will be a minimum of a 275 on a 9.5". My preference will be a 265/30R19 on a 19x9.5" and 285/30R19 on a 19x10.5". I didn't get the chance to do some final measuring last night, so hopefully tonight.

[B21]

Originally Posted by Steve Jarvis

I was only testing the 18" front 19" rear for clearance. I moved the current rear wheels to the front and mounted my sons autocross 19" in the rear, to do a test drive and see if they would rub. It will be 19" front and rear.

I have run as wide as a 285 on the front of my cars and I have found that the tire design has a bigger impact on a tire following grooves than the tire size. The alignment is also a factor as well as trying to decide the impact on the Z4's electric steering. Of course the roads in my part of the US may differ from your roads.

My front will be a minimum of a 255 on an 8.5" and the rear will be a minimum of a 275 on a 9.5". My preference will be a 265/30R19 on a 19x9.5" and 285/30R19 on a 19x10.5". I didn't get the chance to do some final measuring last night, so hopefully tonight.

I tried 255/35 19 and 275/35 10 on a set of 437M M2/M3 wheels with stock offsets..the front end felt very heavy and didn’t transition well trying to move quickly through bends..so that set now have 235/35 19 and 275/30 19

I brought the rear camber in by about a degree to reduce tramlining..

There is some debate on the stability control system that suggests you shouldn’t really exceed a 1% to 1.5% differential between front and rear rolling radius..

I did have a major issue once when I inadvertently had fitted an oversized front resulting in a 3.2% difference..

Th4 front offset due the design of the front steering assembly does show some sensitivity to changes..

I’ve run Michelin MP4S and GY Assy 5 but my favourite is now Continental Sports Contact 7..not sure if they are available in the US..

[Steve Jarvis]

B21,

Thanks for the useful information.

I believe I will stick with a 255/30R19 front and 275/30R19 rear (after measuring). Now I'm trying to decide on the appropriate wheels. The right answer is a 9" front and 10" rear but unfortunately they aren't offered in the right offsets or those widths in the wheels I'm considering.

The easy answer is the VMR V701 in a 19x8.5" +35mm front and 19x9.5" +45mm in the rear. The issue is they're heavy and the rears aren't currently available. My other option is the Apex SM-10 which is lighter and looks better but the best fit is a 19x9.5" +33mm front and a 19x10.5" +45mm offset rear. That's within spec for the 255, but the 275 has a recommended rim range of 9.0-10.0.

[Steve Jarvis]

Here's a quick update. I'm going to order the wheels on Black Friday (to hopefully get a little discount). I'm playing with the idea of a 19x9.5" +35 front with a 265/35R19 and a 19x10.5" +45 rear with a 285/30R19. This will keep the front to rear height closer and both tires will be within the wheel specs. I have also decided to go with the Apex VS-5RS which is a forged one piece wheel. I will need to move the rear heat shield in slightly (where it attaches to the inner fender liner) and modify the fender liner at the 12 o'clock position (at the outer fender lip) to get this to clear. I'm going to install 12mm spacer with my "test fit" wheels tonight to get a better idea of the outer wheel/tire position and what needs to be modified.

[Steve Jarvis]

Okay I'm 95% I'm going with the 265/285 9.5"/10.5" setup. Attached is a picture of my son's autocross wheels/tires mounted. These wheels are 19x9.5" with 275/30R19's. They are very wide at the tread. The picture shows them mounted with 12mm spacers. This setup can be turned lock to lock (barely) without rubbing, but isn't really street-able. The rear rubs the plastic inner fender liner at 12 o'clock (not the metal fender lip), but is fine without the 12mm spacer. My proposed setup will position the wheel lip in the same place, but the tire will be inward. The front is effectively a 33mm offset, so my proposed 35mm offset wheel lip will be inward 2mm. The tire in the picture has a tread width of 10.2" (259mm). The proposed 265/30R19 has a tread width of 9.6" (244mm). The front tire tread will move in 7.5mm due to the size difference and 2mm due to a 35mm offset versus the 33mm offset in the picture. Total difference is 9.5mm (3/8").

[B21]

Wonder how the rears will cope with bumps..the rear camber increases as the suspension compresses but will it tuck in enough as the wheel travel upwards?

[Steve Jarvis]

It is very close. I drove the left front wheel up on a ramp, which compresses the right rear wheel. The setup in the picture hits the plastic liner on the outside, but not the metal fender/qtr. Only the tread area of the sidewall compresses all the way up to the liner and the actual 285 tread width is less than the tire in the picture. Plus the picture shows an effective 33mm rear offset versus the 45mm of the wheels I'm purchasing.

I did the opposite the compress the front wheel up into the fender.

[Steve Jarvis]

I was replacing my M4's brake fluid this weekend, so I decided to try the wheels on the the Z4. Definitely taller than I would want and the clearance to the front strut is almost zero. Either way, I was surprised they would even bolt on. My front tire wasn't completely straight, but the tire clearly stick out of the fender a little. These are 265/30R20 on 20x9" +29mm front and 285/30R20 on 20x10" +40mm rear.

[Steve Jarvis]

M4 wheels

[B21]

Originally Posted by Steve Jarvis

M4 wheels

Did you take it for a drive?

[Steve Jarvis]

In the neighborhood, but I never intended to install tires this tall. I was surprised that it cleared the front strut. It rubbed at full steering lock, but not as much as I was expecting. The rear would clearly rub the plastic fender liner (at the 12 o'clock position) over a large bumps.

Given wheel availability, tire size differences and tire/wheel fitment, I'm still leaning toward the 265/9.5 and 285/10.5 on 19" wheels. It's always a compromise between steering feel, front end grip and handling balance. I'm sure I'll do suspension changes, but I'll probably wait until next year.

[B21]

Originally Posted by Steve Jarvis

In the neighborhood, but I never intended to install tires this tall. I was surprised that it cleared the front strut. It rubbed at full steering lock, but not as much as I was expecting. The rear would clearly rub the plastic fender liner (at the 12 o'clock position) over a large bumps.

Given wheel availability, tire size differences and tire/wheel fitment, I'm still leaning toward the 265/9.5 and 285/10.5 on 19" wheels. It's always a compromise between steering feel, front end grip and handling balance. I'm sure I'll do suspension changes, but I'll probably wait until next year.

My tyres are not optioned in a 285/30 so even I was tempted it’s a no from me..

Look forward to 2024..

[Steve Jarvis]

I’m trying to decide between Motorsport Gold and Anthracite. What do you think?

[MRCW]

Originally Posted by Steve Jarvis

I’m trying to decide between Motorsport Gold and Anthracite. What do you think?

IMO, nothing gold looks good on a car... not even the paint

[B21]

Ditto …gold tend to look good only in the eyes of the owner…maybe on a black car?

[MRCW]

Originally Posted by B21

Ditto …gold tend to look good only in the eyes of the owner…maybe on a black car?

You mean like a redneck Bandit Trans AM?

[Steve Jarvis]

"look good only in the eyes of the owner" Isn't this the point.

I guess we ask, not because we need someone's approval or because we want to know which they would choose, but because we want to know why they would make that choice. It leads to points of view we may not have considered.

I agree that gold is a little "out there", but it's a nice shade and both Porsche and BMW have offered top models with gold wheels (CSL & GT3RS).

Anthracite is a safe option and also boring and "played out".

Then there's the red interior in my car. Gold wheels on a white car with red interior may be too much going on.

I'm not totally in love with either look, but don't see a better option.

[MRCW]

Originally Posted by Steve Jarvis

"look good only in the eyes of the owner" Isn't this the point.

I guess we ask, not because we need someone's approval or because we want to know which they would choose, but because we want to know why they would make that choice. It leads to points of view we may not have considered.

I agree that gold is a little "out there", but it's a nice shade and both Porsche and BMW have offered top models with gold wheels (CSL & GT3RS).

Anthracite is a safe option and also boring and "played out".

Then there's the red interior in my car. Gold wheels on a white car with red interior may be too much going on.

I'm not totally in love with either look, but don't see a better option.

Classic silver... I'm a fan of light colored wheels on light colored or red cars...

I have a meteorite silver (dark grey metallic) Aston Martin with aftermarket dark anthracite wheels, a guards red Porsche Boxster with classic silver and my mineral white Z4 also with classic silver wheels...

My triple black AMG GLE has black wheels and I'm considering a switch on the wheels because it has to much black but my wife drives it and she loves the all black...

To each their own!

[B21]

Originally Posted by Steve Jarvis

"look good only in the eyes of the owner" Isn't this the point.

I guess we ask, not because we need someone's approval or because we want to know which they would choose, but because we want to know why they would make that choice. It leads to points of view we may not have considered.

I agree that gold is a little "out there", but it's a nice shade and both Porsche and BMW have offered top models with gold wheels (CSL & GT3RS).

Anthracite is a safe option and also boring and "played out".

Then there's the red interior in my car. Gold wheels on a white car with red interior may be too much going on.

I'm not totally in love with either look, but don't see a better option.

The abbreviated answer was from someone who has often pondered what colour to do wheels, along with brake calipers...

I've done silver in various shades, gloss black, satin black, matt black, and though of bronze, gold and cut alloy versions..

I like gloss black but it never looks good in photos..my next journey is an anthracite in a certain version..

[B21]

Anthracite 437Ms

No diamond cut