Z8 Tires Sizes, Wheel Offsets and Weights

[macfly]

The wheel offsets for the Z8 are 20mm front, 22mm rear.

Here is a list of tire sizes suitable for BMW Z8.

Front stock tire size:
245/45/18 339mm in radius
Front upgrade tire size:
255/40/18 331mm
245/40/19 339mm
255/35/19 331mm
265/40/19 - GM
245/35/20 340mm
255/35/20 343mm

Rear stock tire size:
275/40/18 339mm in radius
Rear upgrade tire size:
285/40/18 343mm
295/35/18 332mm
275/35/19 338mm
285/35/19 341mm
295/30/19 330mm
285/30/20 340mm

The chart suggests that the best front and rear combination is 245/40/19 front / 275/35/19 or 285/35/19 rear in 19", however GM has been running 265/40/19 - 285/35/19 and is very keen on that combo as the wider front footprint gives increased grip and neutralizes understeer.


This is a weight comparison chart for some of the common tire/wheel combos

wheel...................tires...............................front............................................rear

Stock.....................Bridgestone RE040r/f........62lbs/28.1k - 245/45/18..................67lbs/30.4k - 275/40/18
rims alone..............18 x 8 / 18 x 9................29lbs/13.1k...................................31lbs/14.1k

Alternative tires on stock OE 18" rims
Stock.....................Bridgestone RE-11...........61lbs - 245/45/18...........................66lbs - 275/40/18
Stock.....................MPSport 2......................54.5 lbs - 245/45/18........................58.5 lbs - 275/40/18


19"
BBS RGR 19"...........Michelin PS2....................46lbs/20.8k - 265/35/19..................50lbs/19.5k - 285/35/19

BBS RGR 19"...........Yokohama Advan Sport.....49lbs/22.2k - 265/35/19..................53lbs/23.6k - 285/35/19

BMW Style 166 19"...Conti Sport Contact 2........53 lbs/24k - 255/40/19....................59.5 lbs/27k - 285/35/19
rims alone..............19 x 8.5 / 19 x 9.5............26lbs/11.8k...................................29 lbs/13.1k


20"
BBS RS-GT 20"........Michelin PS2....................48lbs/21.8k - 255/40/20..................52lbs/23.6k - 285/35/20

Hamann 20"............Michelin PS2....................61lbs/27.7k - 255/35/20..................63lbs/28.6k - 285/30/20
rims alone..............20 x 9 / 20 x 10.5............31lbs/14.1k...................................36 lbs/16.3k

BMW M Sport 20".....Pielli P Zero.....................61lbs/27.7k - 255/35/20..................66lbs/30k - 295/30/20

Alpina Rims 20".......Michelin PS2.....................57.2 lbs/25.9k - 255/35/20..............58.7lbs/26.6k - 285/30/20
rims alone..............20 x 9 / 20 x 10................31.6lbs/14.3k................................32.5 lbs/16k

[Norcal]

STOCK:
F 18x8, 20mm offset, 120mm lug space, 30 lbs, 245/45/18
R 18x9, 22mm offset, 120mm lug space, 32 lbs, 275/40/18

ALPINA V8:
F 20x9, 20mm offset, 120mm lug space, ??lbs, 255/35/20
R 20x10, 22mm offset, 120mm lug space, ??lbs, 285/30/20

HARTGE WHEELS:
"Classic"
F 20x9 - 18mm offset
R 20x10 - 22mm offset
"Nova"
F 20x9 - 18mm offset
R 20x10 - 28mm offset (I don't understand why so much difference)

One owner (iGuZ8) has mounted on "Nova"
F 255/35/ZR20
R 305/25/ZR20

[macfly]

Wheel Offset: Distance from the center (half way between the inner edge and outer edge) of the rim to the mounting surface that contacts the rotor hub or drum.

If the center of the rim is located outboard of the mating surface, that's negative offset. If the center of the rim is located inboard of the mounting surface, that's positive offset. If the rim center is in-line with the mounting surface, that's zero offset. So, offset refers to the location of the wheel center, relative to the mounting surface.

Negative offset creates a wider track, moves the wheel/tire towards the lip of the fender and creates a deep dished look on the street side of the wheel. Positive offset creates a more narrow track, moves the wheel/tire inwards so they are closer to the brakes and suspension parts and creates a flatter street side appearance.

To measure wheel offset, you begin by measuring the wheel's backspacing. Lay the wheel face down, place a straight edge across the center of the upper edge of the rim (this is the wheel's inside edge), then measure the distance from the mounting surface to the bottom of the straight edge. This gives you the wheel's backspace. Now use the following formula to figure the wheel's offset: Backspace minus 1/2 wheel width = wheel offset. The number will be either positive, negative or zero, as described above.

Too much negative wheel offset can cause interference between the outer edge of the tire and fender lip, place undue stress on the wheel bearings, ball joints and control arms, and cause steering wheel kickback and increased steering effort. Too much positive wheel offset can cause interference problems between the wheels and the brake calipers, other suspension parts, or the inner fender wells. Your best bet is to stay as close to the factory offsets as possible.

If you increase the width of the rims, your new wheel offsets will no longer correspond to the factory offsets. For example, if you keep the same offsets as the original wheels but go to wider rims, you will add an equal amount of width inboard and outboard which may not be what you want. Careful measurements for clearance are critical. This is where recommendations from wheel manufacturers and/or places like The Tire Rack can be very helpful.

[Z8doc]

the Offset for the OEM Z8 18x8 / 18x9 is the same as the 20" Alpina wheels.

Z8
18x8 offset 20mm front 30lbs
18x9 offset 22mm rear 32lbs

Alpina V8 roadster
20x9 offset 20mm front 28lbs (?)
20x10 offset 22mm rear 30lbs (?)

So, with the offsets the same, the larger and lighter MPS PS2s will clear fine front and rear. Most brands other than BMW seem to have a 20mm offset for the front in both 19" and 20" rims but considerable variability in the offsets for the rear. It seems that a 22 - 25mm offset is what most recommend if you are going bigger in the rear. There seems to be enough clearance of the MPS PS2s with that offset.

[stuartsackley]

Do you know if 19x8 and 19x9 1/2 wheels off of a BMW 545,will fit on a Z8?
Thank you.

[macfly]

I think you could find that info from a BMW dealer. I can't help as I have no idea what any of the other measurements for those wheels are.

[Z8doc]

Which particular wheel as there are many available for the 545i and what particular year 545i are you referring too, the e60 or the e61? The M Cross Spoke 101 in the 8x19 front:et 20 and 9 1/2 x 19. et 32 might fit but this same wheel in the 20" version (9x20:et24 front and 10x20:et 24 rear) will fit for sure and can be found on Carlos' red/red Z8 here in the wheel forum -- they are stunning.

The stock offset of et:20 front and et:22 rear for the Z8's 18" wheels should be adhered to as close as possible as if you stray to far, you may need wheel hub centric spacers, which, theoretically, is not as secure as without the spacers.

[stuartsackley]

Which particular wheel as there are many available for the 545i and what particular year 545i are you referring too, the e60 or the e61? The M Cross Spoke 101 in the 8x19 front:et 20 and 9 1/2 x 19. et 32 might fit but this same wheel in the 20" version (9x20:et24 front and 10x20:et 24 rear) will fit for sure and can be found on Carlos' red/red Z8 here in the wheel forum -- they are stunning.

The stock offset of et:20 for the Z8's 18" wheels should be adhered to as close as possible as if you stray to far, you may need wheel hub centric spacers, which, theoretically, is not as secure as without the spacers.

thank you.

[macfly]

wheel with tire weights added to lead post - if anyone has weights of alternative wheel/tire combos let me know and I'll add hem to the list.

[Z8-NL]

I only weighed my front rim/tire. M6 rim plus PS2 and weight was 24.2k
If I get rear rim/tire off I will weigh that as well.

Off course the brembo kit weighs a lot less then stock as well

thanks
Klaus

[gutMD]

My E60 M5 19" Style 166 wheels arrived today.
Stats as follows. (Lighter than I thought they would be)

Front: 19 x 8.5, ET 12mm, 26 lbs
Rears: 19 x 9.5, ET 28mm, 29 lbs

Having Continental Sport Contact 2 mounted and will weigh again when complete and update post.

Weights: rims + tires

Front: 255/40/19, 53 lbs
Rears: 285/35/19, 59.5 lbs.

[Z8doc]

Are you going to need hub centric spacers for the front -- 12 mm offset -- in order to bring the wheel/tire combo back to the same overall position as the OEM wheel/tire setup? The Rear will probably be Ok but will be 16 mm overall more narrow of a stance compared to the OEM -- which I guess would give you less(?) oversteer potentially? GM-- care to weigh in on this question?

[gutMD]

Based on my calculations the rear stance will be entirely unchanged without need for spacers. The front wheels will protrude 14mm giving the front an overall wider and hopefully more aggressive stance, again without need for spacers.

[jawz]

Just put new PS2s on Alpina rims.
FWIW - Here are the weight details:

Alpina Rims:
Front - 31.6 lbs
Rear - 32.5 lbs

MPS 2:
Front (255/35) - 25.6 lbs
Rear (285/30) - 26.2 lbs

This makes a grand total of:
Front: 57.2 lbs each
Rear: 58.7 lbs each

Do these figures square to what others have found? (Just wondering about the accuracy of the weight scale used.)

[Norcal]

Doesn't look like PS2s come in 295/30/20 for the rears... Pirelli might be the best option

[ZMates]

Dinan wheels/PS2 tires

.........tires...........weight
front:..275/35/18..20.8kgs (45.8lbs)
rear:...285/35/18..21.1kgs (46.5lbs)

[ZMates]

BBS Forged Individual:
front: 8.75x19 ET 22
rear: 10.25x19 ET 22

weight with Michelin PS2 (255/40/19, 285/35/19):
front: 19.75kgs
rear: 21.75kgs

[jdillane]

The chart suggests that the best front and rear combination is 245/40/19 front / 275/35/19 or 285/35/19 rear in 19", however GM has been running 265/40/19 - 285/35/19 and is very keen on that combo as the wider front footprint gives increased grip and neutralizes understeer.



it's probably not fair to inquire about such an old post. Have OEM wheels on my 2001 and am thinking of getting the Michelin Pilot Super Sports.

Wondering if GM's preference for 265/40/19 - 285/35/19 has been adopted by any members and would appreciate any feedback.

Thanks!

Okay, it appears the Pilot Super Sports are not available in the above sizes. Is there a concensus preference as to best fitment for OEM wheels?

Thanks again!!

[Z8Mania]

MPS2 are available in the OEM sizes and that's what Id recommend. I'd also point out that GM had made several changes to the suspension so its hard to judge based on tires alone.

[jdillane]

MPS2 are available in the OEM sizes and that's what Id recommend. I'd also point out that GM had made several changes to the suspension so its hard to judge based on tires alone.




Thanks for the quick reply. Odd. Went to the Michelin site and plugged in my specs and was advised:


Your Search :
2001 BMW Z8 Standard
We are sorry. This tire line does not have tires that meet this vehicle's specifications.
We have found other tire lines that do fit your vehicle's specifications

[Z8Mania]

They could say that but I have a set of OEM wheels with MPS2 on them in my garage so I know they made them and I believe they still do. However, they might be switching over to the MPSS and if thats the case you might have to wait... here is what Tirerack says:

http://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Pilot+Sport+PS2&frontTire=445YR8SPORTPS2XL&rearTire=74YR8SPORTPS2&vehicleSearch=true&fromCompare1=yes&autoMake=BMW&autoYear=2001&autoModel=Z8&autoModClar=

Pilot Sport PS2(Max Performance Summer)

2001 BMW Z8
Front: 245/45ZR18
Sidewall Style: Blackwall
Serv. Desc: (100Y)
Load Range: XL
UTQG: 220 AA A Price: $322.00 (each)
Estimated Availability: Fewer than 9
Qty:
Optional Road Hazard Program: Add $20.10 per tire

Rear: 275/40ZR18
Sidewall Style: Blackwall
Serv. Desc: (99Y)
UTQG: 220 AA A Price: $366.00 (each)
Estimated Availability: In Stock
Qty:
Optional Road Hazard Program: Add $22.30 per tire
Add Road Hazard: $84.80
Set of 4: $1,376.00
ADD TO CART

[jdillane]

My mistake. I was looking at the MPSS. Don't think it prudent to wait as my Z still has the Bridgestone RFTs.

[Z8Mania]

I agree- so get the MPS2 and while you wear them out they will be getting the MPSS into the distribution system. :)

[thegunguy]

From member ms23:
Bridgestone Potenza RE-11 on OE wheel in standard sizes.
Front: 59 lbs, 2 oz. Rear: 63 lbs, 4 oz.

I'll add to lead post and normalize the weights to match our "standard". ms23 also had the OE setup weighed (showed 2 & 3 lbs for front and rear respectively). So, I'll gross these up for consistency.

[Norcal]

There is an error here, me thinks... 20" wheels with 19" tires?

BBS RS-GT 20"........Michelin PS2....................48lbs/21.8k - 255/40/19..................52lbs/23.6k - 285/35/19

Also, note how light the Alpina 20s are compared to stock Z8, and they are 1 inch wider at both ends. Must be the tires? I need to weigh my total setup with rubber on.

[Z8Mania]

Good catch. I also noted the savings. I suspect it is due to the tires and maybe the stock wheels have more metal in their spokes? In either event I believe its about 25lbs in unsprung weight savings which works out to something like 75lbs of sprung weight.

[Charles]

I am getting what may be close to the last set of MPS2's on stock wheels. I will ask Dana if he can weigh them, as I don't see that on the list above.

[thegunguy]

If possible, weighing the components prior to mounting would be great.

Nice to hear he found you a set!

[jim]

Ok guys, I'm alittle confused and I'm entering a time when I'll be putting new sneakers on my Z8. I want to use OEM wheels, So, are you saying the PSS's are the hot lick? If not what? They're not in stock yet but I guess worth the wait. Thanks,
Jim
60041

[thegunguy]

The Super Sport are the preferred tire, but it is not available in the OE sizes. It took Michelin quite some time (years) before they brought the PS2 to the OE size. So, you might be waiting a long time if you must have the Super Sport.

A member, ms23 recently equipped the Bridgestone RE-11 on the OE wheel, and it gets pretty good reviews in most places. For right now, it's probably the best replacement, unless you have a guy that can score some PS2s.

[jim]

The Super Sport are the preferred tire, but it is not available in the OE sizes. It took Michelin quite some time (years) before they brought the PS2 to the OE size. So, you might be waiting a long time if you must have the Super Sport.

A member, ms23 recently equipped the Bridgestone RE-11 on the OE wheel, and it gets pretty good reviews in most places. For right now, it's probably the best replacement, unless you have a guy that can score some PS2s.

I need tires, I want PSS's, they don't make OEM rear size.
Is it ok to go w/
245/40/R18 front
275/35/R18 rears
What say you?
Thnx,
Jim
:3gears:

[thegunguy]

I'm probably not a good source. I try to stick with the standard sizes, figuring the engineers sweated the details for a reason. This is in part why I chose to use the 19" wheels from the M5 as well - no guessing on the tire sizes.

That being said, you're looking at a 12.5% reduction in the front and 11.1% reduction in the rear. That seems to be a lot to me, but again, I've only ever gone with the standard sizes.

[jim]

Roger that & appreciated. Homework continues, will advise.
Thnx
Jim
60041

[Z8doc]

I need tires, I want PSS's, they don't make OEM rear size.
Is it ok to go w/
245/40/R18 front
275/35/R18 rears
What say you?
Thnx,
Jim
:3gears:

Front stock tire size:
245/45/18 339mm in radius
Front upgrade tire size:
255/40/18 331mm
245/40/19 339mm
255/35/19 331mm
265/40/19 - GM
245/35/20 340mm
255/35/20 343mm

Rear stock tire size:
275/40/18 339mm in radius
Rear upgrade tire size:
285/40/18 343mm
295/35/18 332mm
275/35/19 338mm
285/35/19 341mm
295/30/19 330mm
285/30/20 340mm

Another option might be the Continental ExtremeContact DW. It has good reviews and is a OEM BMW tire on various models.

See it Continental ExtremeContact DW Sizing (http://www.conti-online.com/generator/www/us/en/continental/automobile/themes/car_tires/performance/extreme_dw_en/hidden/printable_datasheet_en.pdf)

[Z8Mania]

Bridgestones are pretty good tires. If thats whats available, Id go with it.

[thegunguy]

Agreed. Bridgestone or Conti are my #2s behind Michelin, and I've had some great Potenzas over the years.

[Z8doc]

Although the Bridgestones had great grip and handling, I thought there were generally a very noisy tire and the road noise got worse as they wore out. Personally, like the Michelins but the Continentals are equal IMHO and are significanly less expensive so to me that wins out. I have the ExtremeContact DWS preformance all season versions on the X5 and M6 and love them.

[thegunguy]

I put the DWS on the X5 a few months ago, and I'm very pleased as well.

[Norcal]

Anyone remember the Bridgestone S-02 or S-03 (Pole position)? Those were great in their day.

Anyone tried the RE11?

[dogdoc97]

The car is ready, the new headlamp is in, water tested...so I thought lets get some tires now that the PP kit is in; if you all recall they did not want to sell me anything that was not OEM, I.e.the Bridg RFT. Anyway, now the service director tells the tire rep inside the dealership to get me some tires that I would like, asked about the Conti DWS, no go and only shows for the front, Bridgestone Re-11, no go, so I am thinking what the hell is going on. The tire rep tells me that his company is a distributor for many car makers, and that they only carry OEM recommended tires as replacements so once again they lose revenue, I have to be inconvienenced and no one wins. Tomorrow I pick up the car and will go to an independent tire shop, and I will NOT be running 20 inch wheels so thanks to all on this. I would love the ALPINA 20's BUT I am not that driven to spend $10-12K+ by the time I get wheels, tires and the setup underneath. Max

[thegunguy]

I wouldn't put the Conti DWS on the car anyway. It's an all weather tire. D = Dry, W = Wet, S = Snow.

Just order the tires you want from Tirerack, etc.

[Z8Mania]

Id certainly use tire rack to check out the tires that would fit. Again, I posted the link to tire buyer where they have the MPS2 for the stock wheels...

http://www.tirebuyer.com/tirebuyerwicket/home/action/searchByTrim/vTrimChg_454860594/true/tab/Buy%20Tires/selPanel/tireDetailPanel/selectedYear/2001/selectedMake/BMW/selectedModel/Z8/selectedTrim/STANDARD/selectedFitment/FRONT:%20245*fs*45ZR18%2096W%20%20%20REAR:%20275*fs*40ZR18%2099W/sortChanged/false/vfrontWidth/245/vfrontRatio/45/vfrontDiameter/18/vrearWidth/275/vrearRatio/40/vrearDiameter/18/page_0/2/tireCatalogView_selectedItem/176677

Ive bought from them in the past and while they are not cheap they usually have stock.

[Charles]

Ok, you are not going to believe this, but here are the numbers Matt Carver at Peter Pan gave me on my stock wheels with new MPS2's:

Front 54.5 lbs. with 34 psi air 245/45 -18
Rear 58.5 lbs. with 36 psi air 275/40 -18

[macfly]

That makes perfect sense, the tires are saving around 8lbs each being non RF.

[Z8doc]

with 34 psi air 245/45 -18
with 36 psi air 275/40 -18

How much did the air weigh? :D:D::rotflmao:

[Z8Mania]

Fill it with Helium ;)

[Charles]

How much did the air weigh? :D:D::rotflmao:


About 15 grams, but since it is from Peter Pan, that CA air may be a little lighter...anything to reduce unsprung weight, no?

[Z8Mania]

I won't grow up.. ;)

[macfly]

Our rear wheels allow for quite a generous amount of negative camber to be dialed in, which I've used with to try to keep my tire wear even as I'm mostly on twisty, curvy back roads. I just removed my rears, and although the rear wear was very even across the threads I discovered that the very inside edges of the tires were quite badly worn.

I can attribute this to doing some very high speed runs in Oregon, and also some long days on that tour on fairly straight open roads. The lesson in this is if you use an aggressive negative camber at the rear thinking you'll be mostly canyon carving, always double check the very inner edge of the tire for wear if you throw in some more normal open road driving.

The Pirelli rears lasted 4.5 years and around 6,000 miles, the fronts were toast at 3 years and 4500 miles.

[Norcal]

My rears always go first.. seems like 2 to 1 ratio

[Z8Mania]

Especially for non track driving. Its just too fun to put the power down. Also consider if one of your tires is going to blow out- its better off to be a front rather than a rear- those are your stability. Thats why you see the law enforcement always going to knock the rear when they want to spin out a perp.

[macfly]

I guess I'm easy on the gas but hard on the brakes and turn in as I'm always toasting my fronts first on the Z8.

[Z8Mania]

I will be on the lookout for the fronts as well as Ive dialed up the negative camber as much as I can.