19" wheels

D

DrNick

Senior member
 Wickham, Hampshire
Im thinking of changing my zed to a E89 and have seen a couple that might suit however they all seem to have 19" wheels - I'm not that keen on these (tyres/ride quality etc) - if I wanted to change them for 18's would I have to do anything to the speedo etc?

N
 
Wouldn't think so, I believe that the outside diameter of the tyre is the same on either size wheel as the rim is thinner on the 19 inch.

I may stand corrected though!
 
Basically you have to keep the wheel diameter the same, known as the rolling radius. To do that you would have to increase the size of the tyre profile on the 18'' wheel.
For example a style 276 wheel can be 18'' or 19''
An 18'' runs on 225/40/18s and 255/35/18s and a 19'' runs on 225/35/19s and 255/30/19s.
The difference in circumference between the wheels in the example above would remain less than a millimetre whereas if you used the same profile tyres on on an 18'' and 19'' wheel it would be 76mm
Simples
 
Most car,s speedo,s don,t read correct anyhow Nick , you can check exactly with a TomTom satnav or similar .
Ive recently changed my Astravan wheels from the standard 16,s to 18,s & my speedo is now only 1mph out at 30 whereas before it was 3mph out :? always good to know what your car is actually doing when in speed zones on motorway etc :thumbsup:
 
chester2000 said:
Dr Nick,
I'm wanting to change my wheels in the other direction ..from 18" to 19".

Maybe we could be the perfect match :oops:
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I was going to suggest your name. Maybe it's fate.....you will get these 19s sooner or later
 
Thanks guys - this makes sense.

chester2000, - I have yet to buy the car! Shall bear this in mind...

Off to Guildford this morning to have a look...
 
Leave the 19's on it Nick, looks loads better and ride difference isn't that much (I had 18's on my first E89) unless you hit a pot hole!! :cry:
 
I think it depends on the wheel itself - I like your alloys Tim - I have the 19 msport and I like those as well - When looking I would have been happy with your wheels or the ones I got
 
lux said:
Leave the 19's on it Nick, looks loads better and ride difference isn't that much (I had 18's on my first E89) unless you hit a pot hole!! :cry:
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Agreed, I've had E89's with 18s and 19s and it's worth putting up with a slightly firmer ride to get the looks of the 19s. The Msport option adds a bit of class as well.
 
TitanTim said:
+1 the 19s look better, wished i'd specced them now, obviously rubber will be slightly costlier than 18s.
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I think the rubber is a lot more expensive but if you don't do many miles the tyres will be cracked before they're worn ! My car is three with 12k so I'm in that boat.
There is a recommended age that they (tyres) are supposed to be changed irrespective of wear I believe.
 
ronk said:
TitanTim said:
+1 the 19s look better, wished i'd specced them now, obviously rubber will be slightly costlier than 18s.
Click to expand...

I think the rubber is a lot more expensive but if you don't do many miles the tyres will be cracked before they're worn ! My car is three with 12k so I'm in that boat.
There is a recommended age that they (tyres) are supposed to be changed irrespective of wear I believe.
Click to expand...

The runflats can crack prematurely due to the harder compound, my old Cooper S was bad for this but haven't noticed it so much on the latest generation tyres. I think 6 years is probably the max on normal tyres before I would want to change if not covering the mileage but with runflats probably sooner.

Tim.
 
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