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Model specific boards => Golf mk5 => Topic started by: matski on 04 November 2010, 15:36

Title: 17 to 18" Wheels
Post by: matski on 04 November 2010, 15:36

I changed my 17" Monzas to 18" Monza II's, Spoke to VW yesterday and they said i have to get the speedo recalibrated? Never known of this before is it something I should worry about? Any recommendations?!

Cheers

Oly

Title: Re: 17 to 18" Wheels
Post by: Phil1980 on 04 November 2010, 15:41

They are talking bollocks your speedo will just read higher with 18's mine is a few mph out when I compare it to my sat nav,  wouldn't worry about it unless they are going to calibrate it for free.  Are you keeping the 17's?

Title: Re: 17 to 18" Wheels
Post by: matski on 04 November 2010, 15:49

Yer thats what i thought, it could only be a slight difference! So r u saying that the speedo reading will be fast with the 18's? I'm selling the 17's in the classifieds section: http://www.golfgtiforum.co.uk/index.php?topic=171212.0

Title: Re: 17 to 18" Wheels
Post by: Jimp on 04 November 2010, 15:50

If your wheel's rolling radius is the same then it won't change your speedo. If you fitted 18's with huuuuge tyres then it would be out, but with appropriate size tyres it will be fine.

Title: Re: 17 to 18" Wheels
Post by: matski on 04 November 2010, 15:57

Ok, i'll check them out later and compare, how do I know what the rolling radius is?

Thanks

Title: Re: 17 to 18" Wheels
Post by: Jimp on 04 November 2010, 16:06

The best way to get the same size tyres as the factory 18's use.
This site can be handy for double checking:
http://www.miata.net/garage/tirecalc.html

Title: Re: 17 to 18" Wheels
Post by: matski on 04 November 2010, 16:18

Thanks for that. That website says that my speedo is 0.5% out, so when i'm doing 60mph i'm actually do 60.3mph, so its a tiny difference!

Thanks for clearing that up for me.

Title: Re: 17 to 18" Wheels
Post by: nr123 on 04 November 2010, 16:28

There will be no difference!! The overall size of the tyre and alloy combined has not changed.
You've gone from a 225/45/17 to a 225/40/18 (hopefully). The reduction in profile compensates for the increased size of the alloy.

Title: Re: 17 to 18" Wheels
Post by: jeynesey on 04 November 2010, 19:20

225/40/18 :afro:

Title: Re: 17 to 18" Wheels
Post by: Gene Hunt. on 05 November 2010, 11:19

I replaced the standard 17'' monza alloys to Edition 30 alloys & nothing changes other than they look much better. :wink:

Title: Re: 17 to 18" Wheels
Post by: Harris GT TDi on 06 November 2010, 19:40

X2,

I just changed my GT wheels to RS4's and no issues at all with speedo.

:)

Title: Re: 17 to 18" Wheels
Post by: matski on 06 November 2010, 21:18

You wouldn't actually notice an issue with the speedo. it would be giving speed readings that were just inaccurate. Like i've said, when i'm driving along at 60 on my speedo i'm actually doing 60.3.

Title: Re: 17 to 18" Wheels
Post by: AlanD on 07 November 2010, 12:54

Quote from: matski on 04 November 2010, 15:36

I changed my 17" Monzas to 18" Monza II's, Spoke to VW yesterday and they said i have to get the speedo recalibrated? Never known of this before is it something I should worry about? Any recommendations?!

Cheers

Oly

VW are such a bunch of f**king muppets it really does wind me up.

Title: Re: 17 to 18" Wheels
Post by: Snoopy on 07 November 2010, 15:29

Thats what happens when you have fitters (also known as DST/MDSTs) rather than a mechanic. Most are just trained monkeys from a book, who repeat the line 'computer says...'. Very few have any mechanical skills or fault finding skills.
But when most owners don't even know what a dipstick is used for which is why these guys can get away with it.

Title: Re: 17 to 18" Wheels
Post by: simonpolly on 07 November 2010, 17:10

Quote from: matski on 04 November 2010, 16:18

Thanks for that. That website says that my speedo is 0.5% out, so when i'm doing 60mph i'm actually do 60.3mph, so its a tiny difference!


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