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Discussion Starter · #1 ·
2001 320d pre-facelift:

It came with 225x40x18 MV2 wheels, id assume non genuine ones.

Anyway my question is what wheels/tyre size would this car come with at the start/what the speedo was calibrated for as id like to know if its giving an inaccurate reading.
 

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If it is 225x40x18 all the way round, then it is highly possible they are replicas. As for your question, google the words 'rolling radius' to have a better understanding of inaccuracies :thumbsup
 

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2001 320d pre-facelift:

It came with 225x40x18 MV2 wheels, id assume non genuine ones.

Anyway my question is what wheels/tyre size would this car come with at the start/what the speedo was calibrated for as id like to know if its giving an inaccurate reading.
Can you post up the tyre size options for your vehicle?

Should be on a label on the driver door shut.

Once I have the details I will work out the differences for you:thumbsup

Here's one I did earlier:rofl

http://www.bimmerforums.co.uk/forum/f84/1994-e34-525i-what-is-the-widest-rear-t7760/
 

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Discussion Starter · #4 ·
OK the plate in the door [316i/318d/318i/320d] has the following sizes on it:
205/50/17
195/65/15
205/55/16
205/60/15
225/45/17
225/50/16

then in the box below:
225/40/18 triangle symbol
225/45/17 triangle symbol
245/40/17 circle symbol
255/35/18 circle symbol

so my wheel sizes are there, but with the symbols [triangle at front, circle at back] am i right in thinking that by manufacture recommendations 225/40/18 should only be on the car at the front providing it has 255/35/18 at the rear? Or to put it another way, 225/40/18 shouldnt be used on all 4 corners?

I would assume under normal driving it wouldnt make a big difference safety wise, as 18" replica/copies are widely sold and im sure just about half the e46 i see have them fitted.
 

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oem wheels are a staggered fitment
ie the rear wheels are wider and accept the 255 size that you have researched :)
now...the 40 aspects are normally fone to use...they are in the zone for keeping the speedo about right.
if you're determined to to go with bm wheels then i'm sure your existing wheels will fetch a decent price on ebay :)
 

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Discussion Starter · #6 ·
Well i do like the wheels but i think if it didnt come with a nice set of wheels then i would have gone for the 17" instead of the 18" that are on it. Because some of the roads i use are not very good and i always figured the lower the profile the greater the chance of damaging a wheel, plus ive heard the 17" can give a slightly smoother ride.

But my last car was a '98 Seat Ibiza 1.9D so the BMW feels pretty smooth compared to it! And as for the potholes, if you hit one thats bad enough you can damage any wheel no matter what size it is.

Would 17" be any easier on diesel, trip computer doesnt seem to go above 39.7 MPG, i know those things arent 100% accurate but i would have thought it would be a bit better. But i guess it could be to do with driving style as im still getting used to the car as its still pretty new to me.
 

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Discussion Starter · #7 ·
What tyre pressure should be in 225x40x18 tyres when they are on all four corners?

Plate doesnt show this setup, only what 225x40x18 should be on the front IF 255x35x18 are on the rear.
 

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Run the usual tyre pressures. The volume of air will be the same just squished in a different way:hihi

What are the recommended pressures for the tyre sizes listed?
 

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What tyre pressure should be in 225x40x18 tyres when they are on all four corners?
32psi all round is what I've heard everyone averages that I know of. Bit more at the back when carrying luggage or passengers.
 

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i think you'll need to keep the pressure pretty much as bm says whatever tyre size you run ;)
the air in the tyre supports the cars weight and volume of air is not indicative of pressure when in a smaller tyre
 

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Discussion Starter · #11 ·
The plate in my car give pressures and they are different for each size. The only one close is the 225x40x18 at the front, but it doesnt tell me what the rears should be because it doesnt come with 225x40x18 rears from the factory.

32 psi all round is usually a good rule of thumb but many people suggest that the rears be a bit more on BMWs, the plate on the door suggests this also as the rear is always more than the front on all tyre sizes it has listed.
 

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are the increases in pressure consistant across the size ranges?
ie rears 5 psi higher than fronts whatever the size?
iirc the plate on my car lists the difference f to r as a pretty linear 6 psi
hth :)
 

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Discussion Starter · #13 ·
are the increases in pressure consistant across the size ranges?
ie rears 5 psi higher than fronts whatever the size?
iirc the plate on my car lists the difference f to r as a pretty linear 6 psi
hth :)

Yeah pretty much, as far as i can remember its 0.4 bar extra for the rear, or nearly 6 psi. Thats pretty much the way ive worked it out now, putting in the correct 225x40x18 front pressure and putting a bit extra in the rears.

1.8 bar/ 26 psi doesnt seem like very much for the front though
2.2 bar/ 32 psi at rear sounds right though.

 
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