tyre size

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trialsrider
Joined: Sun 30 Apr, 2017 23:24
Posts: 2

  Z3 roadster 3.0i

tyre size

Post by trialsrider » Mon 01 May, 2017 20:55

Hi, i've just bought a 2001 3.0 z3, great car. The only thing i'm not sure about are the tyres, the wheels i believe are bmw style 72 ( 18 x 8 ) and the tyres are Toyo tr1 225 x 40x18 all round. would this size be ok as they look small on the rear so any idea what size it should be.
Also why do i see people running a lower profile tyre on the rear, say a 35 on the back with a 40 on the front. Any help and ideas would be great.Cheers.

mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 803

  Z3 roadster 1.9

Re: tyre size

Post by mrscalex » Mon 01 May, 2017 23:04

18" isn't a common Z3 size. You'd expect 16" with 225s all round or 17" with 225 front 245 rear more normally. It's possible they were a build option. But if so I think I'd expect them to be staggered, ie a wider rim at the rear to accept a wider tyre. And possibly wider than 8J.

If 17s run 245 as standard you'd certainly expect the same as a minimum for 18s, maybe 255s. So on balance it doesn't sound standard or making the most of the wheel, I might be wrong, others will know better than me.

The lower profile goes hand in hand with a wider tyre. I think the 35/40 is a ratio not an absolute size.
ImageImage
1999 Z3 1.9 Boston Green (Dimitri) - My brother's car owned from new and restored by me
2001 Z3 2.2 Topaz Blue (Trudy) - My car rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Okus) - Project car waiting for a new engine
2001 Z3 2.2 Topaz Blue (Debra) - Donor car/breaker
1998 Z3 1.9 Boston Green (Allsworth) - Donor car/breaker now gone to Z3 heaven
Always happy to try and help with spares :)

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Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 10010

  Z3 roadster 1.9
Location: Cheshire

Re: tyre size

Post by Robert T » Mon 01 May, 2017 23:20

Depends upon whether the car had a staggered setup. This is normally a wider rim on the rear. For example the ///M had 225s on the front and 245s on the rear. It is common to see a 255 on the rear on the same rim. The 35 or 40 is a percentage of the tyre width, so to keep the sidewall the same you decrease the percentage as you increase the width. AFAIAA the largest factory option was 17inch.

Cheers R.

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Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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4wheels
Joined: Sat 24 Sep, 2016 20:42
Posts: 71

  Z3 roadster 3.0i

Re: tyre size

Post by 4wheels » Tue 02 May, 2017 15:41

are all BMW wheels the same? PCD, hub size etc?
looking around on ebay, there isnt many e36/z3 wheels on for sale.

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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2221

  Z3 roadster 1.9

Re: tyre size

Post by BladeRunner919 » Tue 02 May, 2017 16:06

4wheels wrote:are all BMW wheels the same? PCD, hub size etc?
looking around on ebay, there isnt many e36/z3 wheels on for sale.
Pretty much. Some have a larger centre bore (E39 wheels, for example) but that can be resolved with spigot rings. Not sure what you're searching for on ebay, but there are hundreds of wheels for sale.

Howard Adams
Joined: Mon 10 Oct, 2016 16:39
Posts: 44

  Z3 roadster 3.0i

Re: tyre size

Post by Howard Adams » Tue 02 May, 2017 17:14

Hi, iv also a 3.0i which also had 18 inch wheels on which definitely caused tram lining. Fitted new 16 inch wheels (original size),this transformed the handeling and the ride and basically made the car a superb drive.
So do you want the looks or the superb drive?.... difficult one.
Z3's are renowned for this tram lining and it's normally a combination of wheel size, condition of tyres and worn suspension.
H

4wheels
Joined: Sat 24 Sep, 2016 20:42
Posts: 71

  Z3 roadster 3.0i

Re: tyre size

Post by 4wheels » Tue 02 May, 2017 18:29

mines got 15" ones, dont think they are standard.. or its an early car, and just look a little old fashioned... i was thinking 17s but they would make it handle a bit odd like u say.

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Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 10010

  Z3 roadster 1.9
Location: Cheshire

Re: tyre size

Post by Robert T » Tue 02 May, 2017 19:11

The standard wheel on the prefacelift 1.9 was the 15" pepperpot. The standard wheel on the prefacelift 2.8 was the 16" Z-star. The standard wheel on the ///M was the staggered 17" roadstar. I paid extra to have the Z-star option on my car. Not sure of the other model's standard wheels, but the sports had a cross-spoke design.

Cheers R.

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Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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Brian4
Joined: Mon 19 Dec, 2011 19:02
Posts: 536

  Z3 roadster 3.0i
Location: Hinckley

Re: tyre size

Post by Brian4 » Tue 02 May, 2017 20:56

The standard wheels on a 3.0i were the 16" style 64 8 spoke wheels with 225 50 16 and the 3.0i sport had the style 78 17" with 225 45 17 front and 245 40 17 rear
Brian
3.0I Topaz Blue


2000 E36/7 Z3 3.0i
2016 F31 335d
2015 F21 118i

trialsrider
Joined: Sun 30 Apr, 2017 23:24
Posts: 2

  Z3 roadster 3.0i

Re: tyre size

Post by trialsrider » Fri 05 May, 2017 11:14

Thanks for all the answers you have all given , i've got some more details about the wheels fitted and they are as follows- front style 72 18x8 ET47 , Rear 18 x 8.5 ET50 , they all run 225 40 18 tyres at the moment, thinking do i go for bigger tyres on the rear or just change it all back to standard and run 16'' style35 wheels that are 7'' wide with a ET 46.
At the moment even the 18'' wheels with 225 tyres look a little lost inside the rear arches.

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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2221

  Z3 roadster 1.9

Re: tyre size

Post by BladeRunner919 » Fri 05 May, 2017 12:29

If your concern is about the wheels looking lost in the arch, then really the only option is to lower the car to reduce the gap. All the different combos of wheel and tyre are designed to keep the overall circumference of the tyre the same (the bigger the wheel, the shallower the sidewall). If you put a tyre with a physically bigger sidewall, you would increase the circumference of the tyre, meaning your speedo would under-read etc...

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Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 10010

  Z3 roadster 1.9
Location: Cheshire

Re: tyre size

Post by Robert T » Fri 05 May, 2017 13:54

Or fit spacers...

Cheers R.

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Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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