# confused over wheel sizes



## AwesomeJohn (Apr 25, 2006)

9J = wheel width
18 = wheel diameter
ET = offset
5x112 = PCD (pitch circle diameter) 5 being the number of wheel bolt holes. 112 is the spacing of the holes in mm.

ET45 means the wheel will stick out an extra 10mm (the lower the ET the further the wheel will stick out) Just check you have the extra clearance, if so they'll be fine.


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## jbell (May 15, 2006)

AwesomeJohn said:


> ET45 means the wheel will stick out an extra 10mm (the lower the ET the further the wheel will stick out) Just check you have the extra clearance, if so they'll be fine.


This will depend on the wheel width


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## AwesomeJohn (Apr 25, 2006)

Good call, i was assuming we were still talking about 9"s!

You know what they say about assumption? :?


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## McKenzie (Dec 25, 2008)

This may be of some help http://www.rimsntires.com/rt_specs.jsp
Seems to make things clearer when a computer tells you what will be happening.


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## jbell (May 15, 2006)

The 8" ET45 wheel will give you 20mm more inner clearance and sit 6mm further in the arch than the OEM 9" ET52 wheel.

Tyres will also factor in as a 255/40 R18" tyre is too wide for an 8" wide wheel but a 245/40 R18" will fit (with a little side wall bulge).


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## jbell (May 15, 2006)

para999 said:


> just been and checked my tyre size is 245/40/R18
> but on that tyre calculator posted by McKenzie with the dimensions put in it says"Package will stick out 10 mm (0.4'') farther. Acceptable for most cars. " if i've done it right i.e original on left proposed on right. would this seem about right ? the last thing i want is to have to replace the tyres as well. only done 1,500 on the ones fitted.


I use this one, very accurate http://www.1010tires.com/WheelOffsetCalculator.asp


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## jbell (May 15, 2006)

para999 said:


> jbell said:
> 
> 
> > para999 said:
> ...


I don't know where you are getting these figures from, when I put the current wheel specs at 9" wide ET52 and the new wheel specs at 8" wide ET45 then I get the new wheel to give 20mm more inner clearance and 6mm further in.

It will be fine, you could even put spacers on to fill the arches


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## steeve (Jul 8, 2010)

Why not get the right wheels, then you wont have to worry.
As they say why spoil the ship for an 'apeth of tar?


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## mrdemon (Apr 20, 2005)

you don't want to put a 245 tyre on an 8" rim


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## m-a-r-k (Nov 17, 2009)

mrdemon said:


> you don't want to put a 245 tyre on an 8" rim


Audi do! TT Sport model is 17" x 8J 245/50 tyres according to brochure.


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## sixdoublesix (Nov 3, 2009)

mrdemon said:


> you don't want to put a 245 tyre on an 8" rim


yes you can, I have 19x8 and my 245's fit perfectly. Also running 12/15 spacers to let it sit flush..

No idea why the OP dont go for 245/35's thou. 40 seems a bit high walled?

http://www.********.co.uk/forum/download/file.php?id=11071&t=1


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## 12snowy (Dec 4, 2009)

Although tyre size the same on 2.0 Coupe and TTS the alloy wheel may have a different offset possibly ?
The may be the cause of rubbing.


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## mrdemon (Apr 20, 2005)

quote
"yes you can, I have 19x8 and my 245's fit perfectly"

I would not say a perfect fit, but they will go on, I would not do it myself.


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## sixdoublesix (Nov 3, 2009)

mrdemon said:


> quote
> "yes you can, I have 19x8 and my 245's fit perfectly"
> 
> I would not say a perfect fit, but they will go on, I would not do it myself.


Because?


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## mrdemon (Apr 20, 2005)

you buy a tyre it's in a fixed shape, the ideal rim is always listed

if you go off the ideal the tyres will be either streched or it will be squashed, fitting a wider tyres on a thin rim will give the tyres less support.

I always buy the best tyres on the market at the time, I am always sure to get the ideal fit to give me 100% the performance the tyre was design for,ie not streached or squashed.


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## sixdoublesix (Nov 3, 2009)

mrdemon said:


> you buy a tyre it's in a fixed shape, the ideal rim is always listed
> 
> if you go off the ideal the tyres will be either streched or it will be squashed, fitting a wider tyres on a thin rim will give the tyres less support.
> 
> I always buy the best tyres on the market at the time, I am always sure to get the ideal fit to give me 100% the performance the tyre was design for,ie not streached or squashed.


The tyres wont have less support, a smaller tyre shouldnt be stretched I agree, but going bigger (to the rims limit) will only increase the width, tyre wall height and yes give a different shape less squared but theres no danger in doing so.

i.e going from a 234 35 19 to a 245 35 19 (width increase of c.10mm + Wall height increase of c.8mm + roling diamiter c.50mm and speedo out i.e 60mph will really be 60.6mph)

Best tyre is a matter of opinion, vehicle and driving style


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## mrdemon (Apr 20, 2005)

"The tyres wont have less support"

ofcourse it will 
with the tyre sitting there on it's on is wider than the rim, so there fore less support then if you had a 9" rim

but as you are not buying a premium tyre I guess it does not matter that much.


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