Tyres versus snow.

corporal · Post by **corporal** » Fri 19 Nov, 2004 12:27

I have owned a Jan 1998 Z3 2.8 auto for around 4months and have recently joined the forum. Have read all the advice ref tyres ( currently have Continentals installed 225/45 at the front and 245/50 at the rear.
In the damp and dry handles well, in snow well !!!!!

Thinking of installing set of GoodYear Eagle F1's or Michelin Sport' s for the winter.

Anyone have an experience or advise for their use in a typical scottish winter ???

AndyBass · Post by **AndyBass** » Fri 19 Nov, 2004 12:55

Corporal, welcome. Do a search on "tyres" and you will find plenty of threads to help you come to a decision, but the general concensus is Goody F1's. As to how good they are in snow is a matter of opinion

garyw · Post by **garyw** » Fri 19 Nov, 2004 14:11

I think the right foot dictates how good any road tyre will be. or only snow tyres would perhaps be the way forward.
garyw

greg_ch · Post by **greg_ch** » Fri 19 Nov, 2004 15:24

We get quite a bit of snow here in Switzerland and I can reccomend the Dunlop Winter Sports M3 tires for thier snow/slush/wet performance and imo they are pretty good in the dry.

S1 AVV · Post by **S1 AVV** » Fri 19 Nov, 2004 20:41

corporal, just about to change all 4 of my tyres to eagle f1 gsd3. currently running pilot sports and feel they are a bit twitchy in wet conditions. living in moray i've the same concerns about the snow, obviously winter tyres are the best choice but i can't really justify buying a set as the amount of days it actually snows. as for alternatives to this problem, a couple of slabs of concrete in the boot and a light foot

i got a few quotes for 4 eagle f1's recentley for tyres sizes 245/40/17 & 225/45/17
kwick fit £600
black circles £427 Pilot sports 2 £522
My Tyres. co. uk £400 £509
Topgear.co.uk £408 £500

si

Caspar · Post by **Caspar** » Sun 21 Nov, 2004 15:35

I wrote in the thread New Tyres for my Z3 about Nokian RW Winter tires and after it started snowing this week, they have really been tested in snowy conditions, and I still think they are great.

Played around with the car today and photographed it, really fun, and again... great tires (a bit slippery on ice though since they are without spikes..)

Check out the pictures way down in this thread It's snowing (it's from a Swedish forum so I guess that most of you cant read the text thought..

)

c_w · Post by **c_w** » Sun 21 Nov, 2004 20:01

S1 AVV wrote:corporal, just about to change all 4 of my tyres to eagle f1 gsd3. currently running pilot sports and feel they are a bit twitchy in wet conditions. living in moray i've the same concerns about the snow, obviously winter tyres are the best choice but i can't really justify buying a set as the amount of days it actually snows. as for alternatives to this problem, a couple of slabs of concrete in the boot and a light foot

i got a few quotes for 4 eagle f1's recentley for tyres sizes 245/40/17 & 225/45/17
kwick fit £600
black circles £427 Pilot sports 2 £522
My Tyres. co. uk £400 £509
Topgear.co.uk £408 £500

si

I've put 255/40/17s GSD3s on the back of mine; these are the same overall diameter of the front 225/45/17s (much closer match than the standard 245/40s anyway). The price is virtually the same too.

Not sure why they [BMW] chose these 2 particular tyre sizes as t he overall rolling diameter is obvisouly not the same when the 2 are put together, though this combo is fitted to all 3-series/Z3s with 17" wheels.

The other alternative is fitting a 215/45/17 tyre which may be slightly lower profile at the front but also slightly narrower, perhaps making it less likely to tramline (or reduce it at least), something the Z3 is really bad for.

Caspar · Post by **Caspar** » Sun 21 Nov, 2004 21:37

S1 AVV wrote:corporal, just about to change all 4 of my tyres to eagle f1 gsd3. currently running pilot sports and feel they are a bit twitchy in wet conditions.

I used to have Pilot Sport 2 on the M Roadster. AS You say, very nice tires until it gets wet. If I had to choose only one set of tires for both summer and winter, it would be Pirelli P Zero Nero.

They give at least 99% of the performance of the Pilot Sports in dry conditions but they don't lose it all when it gets wet as the PS2 does.

c_w: Correct! They (BMW) put on a size that's make no sense according to me. As you say putting on 255/40 on the back makes the diameter the same back vs front.

I addition to this, to get the same width vs the rims width you have to go up another step to 265/40 (or 215/45 - 255/40), since the difference between front and back rims are 1½ inch ~38mm. This makes the back tire a bit larger then the front but it looks better with larger back-tires then larger front-tires.. The difference is just as big as BMW original mismatch, but the other way around..

corporal · Post by **corporal** » Mon 22 Nov, 2004 14:55

Thanks every one for your advice.

Had some snow this week and even on Continentals ( and a light right foot) I managed as well as any one else. ( couple of waggles)

The currently installed boots have plenty of life in them yet , so plan to a see how the winter pans out. ( it cannot snow from now until april ?? )

Previous experience to date with michelin sports on a 530 and 320 was positive, and my better half's 320 auto has a set. I certainly felt better in the snow on sat in the 320 , then its older than and not mine !!

S1 AVV · Post by **S1 AVV** » Mon 22 Nov, 2004 20:38

[/quote]I've put 255/40/17s GSD3s on the back of mine; these are the same overall diameter of the front 225/45/17s (much closer match than the standard 245/40s anyway). The price is virtually the same too.
[quote]

you'll have to excuse my ignorance, surely diameter is governed by profile

when looking at the zed side on, the front wheel does look bigger than the rear but i had thought it was the profile differance

Caspar · Post by **Caspar** » Thu 25 Nov, 2004 17:23

S1 AVV wrote:you'll have to excuse my ignorance, surely diameter is governed by profile

Well, the profile only defines the proportion of the tires hight vs the width, /45 means that the tires hight is 45% of its width which makes a 255/40 tire more compatible with the 225/45 tire.

225mm x 45% = 101,25mm

245mm x 40% = 98mm
255mm x 40% = 102mm

Remember that if You calculate on the total diameter of the wheel you must multiply the tires hight with 2.

S1 AVV · Post by **S1 AVV** » Thu 25 Nov, 2004 18:23

thanks casper, i understand now

however if your changing the profile height, then your altering the total diameter, how much of an effect will this have on the speedo accuracy

Caspar · Post by **Caspar** » Fri 26 Nov, 2004 20:28

S1 AVV wrote:thanks casper, i understand now

however if your changing the profile height, then your altering the total diameter, how much of an effect will this have on the speedo accuracy

Let's look at while at the math and it will be clear.

245/40-17" = 245 * 40% * 2 + 17" * 25,4mm/inch = 627,8mm
245/45-17" = 245 * 45% * 2 + 17" * 25,4mm/inch = 652,3mm
255/40-17" = 255 * 40% * 2 + 17" * 25,4mm/inch = 635,8mm

652,3 / 627,8 = 103,9%
635,8 / 627,8 = 101,3%

ie with 245/45 tires your speedo will show 3,9% slower speed and with 255/40-17" it will show 1,3% slower speed then with the original tire-size. I don't consider that a problem since speedos always shows to high speed with original tiresizes. In Sweden a difference from the original diameter up to 5% is legal.

A warning about changing tire-sizes though. The ASC+T system malfunctions if one pair of tires are changed around 2% or more and the other pair aren't..

I don't suffer from ASC+T problems since the Z3 M doesn't have that system until later models (S54 powered). So if a put on summer tires on these rims again (hopefully I'll by new summer rims in 19") it will be 265/40-17, which gives the same tire width vs rims width as the front tires (225/45) and a slightly larger back-wheel.

S1 AVV · Post by **S1 AVV** » Fri 26 Nov, 2004 21:06

never thought maths could be so fun

, so the differance is negilable then.

A warning about changing tire-sizes though. The ASC+T system malfunctions if one pair of tires are changed around 2% or more and the other pair aren't..

after being convinced to change the rear to 255/40/17 on the rear and leave the fronts at 225/45/17, i have asc/t, so i'm guessing i'll be leaving them standard

Caspar · Post by **Caspar** » Sat 27 Nov, 2004 00:34

S1 AVV wrote:never thought maths could be so fun , so the differance is negilable then.
A warning about changing tire-sizes though. The ASC+T system malfunctions if one pair of tires are changed around 2% or more and the other pair aren't..
after being convinced to change the rear to 255/40/17 on the rear and leave the fronts at 225/45/17, i have asc/t, so i'm guessing i'll be leaving them standard

Fun that you liked the math!!

Well, I had 225/45-17 as rear tires on my old Z3 2.8 during the winter and they are 634,3mm in diameter (almost like 255/40), with no problems. By listening to others, my guess is about 2% or more change in diameter on one pair only gives problems. The 255/40 tires are as we concluded above only 1,3% larger.

I know that a lot of the Z3 drivers in Sweden have changed their back tires to 255/40 and I haven't heard of any problem with the ASC+T on their cars.

S1 AVV · Post by **S1 AVV** » Sat 27 Nov, 2004 11:52

thanks again for all that info, we'll give 255's a go then

S1 AVV · Post by **S1 AVV** » Wed 01 Dec, 2004 20:12

fitted the 255/45/17 f1's to the rear today no adverse effects with the asc+t, the rear of the zed looks pretty phat

and it's evened out the sidewall height between front and rear

cheers si

Caspar · Post by **Caspar** » Thu 02 Dec, 2004 22:24

S1 AVV wrote:fitted the 255/45/17 f1's to the rear today no adverse effects with the asc+t, the rear of the zed looks pretty phat and it's evened out the sidewall height between front and rear
cheers si

I truly hope it was 255/40-17 not /45 you put on after all that math!!

S1 AVV · Post by **S1 AVV** » Fri 03 Dec, 2004 08:11

typing error yep /40

Dav · Post by **Dav** » Fri 03 Dec, 2004 18:26

There must be a maximum tyre width you can put on a wheel. How do you know what this limit is?

Dave L

S1 AVV · Post by **S1 AVV** » Fri 03 Dec, 2004 19:09

this is not gospel, but 20mm larger width than original size is the maximum.
found this link whilst serching for info about tyres

www.chris-longhurst.com/carbibles/index.html

Caspar · Post by **Caspar** » Fri 03 Dec, 2004 19:48

S1 AVV wrote:this is not gospel, but 20mm larger width than original size is the maximum.
found this link whilst serching for info about tyres

www.chris-longhurst.com/carbibles/index.html

Doesn't that depend on what tires the manufacturer puts on by default? The rear tires on E36 M3 and Z3M are very slim.

Actually, you can put on much wider tires then that, the limit is rather the looks and the function of the tires. Ie, putting on 285's on the original 9" wheel (=229mm wide) looks like **** and the stability in the tire is gone.

I'd say, up to 35-40mm wider then the wheels width is maximum. Front tire on Z3 are approx 35mm wider (225mm - 7,5" x 25,4mm/" = 35mm). To get the same width vs wheel width on the rear you'd need 265 as mentioned above.

Slimmer tires work nice but that might look truly bad as well. One of the Swedish Z guys runs 255's on 12" wide wheel at the back and 225's on 10" wide wheels in front. Performance is great but personally I'd don't like the look of it.

Dav · Post by **Dav** » Fri 03 Dec, 2004 20:19

S1 AVV,
That is an excellent link. According to the calculations it would appear that 255 is as wide as you should go on the 8.5 wheel, which I believe is on the rear of the 2.8. Let us know how you get on.
Dave L

Caspar · Post by **Caspar** » Fri 03 Dec, 2004 22:13

DAVE L wrote:S1 AVV,
That is an excellent link. According to the calculations it would appear that 255 is as wide as you should go on the 8.5 wheel, which I believe is on the rear of the 2.8. Let us know how you get on.
Dave L

If it's an 8,5" wheel, I definitely agree that 255 is as wide as you should go. It must be perfect if the front tires is 225/45-17 on 7,5" wheels, the same width vs wheel and the same hight.

zroadster.net

Tyres versus snow.

Tyres versus snow.

wide rear

Re: wide rear