safe to change rear alloy size to match front alloys?

[omodos]

ok thanks again , will ask a tire fitter shop what i can get away with.....all i know is that my setup is staggered the front tires are 3cm narrower than rears and also 1.5cm 'shorter' less in diameter , the rim diameter is the same i.e 19"

[TwinsPoppa]

Originally Posted by omodos

ok thanks again , will ask a tire fitter shop what i can get away with.....all i know is that my setup is staggered the front tires are 3cm narrower than rears and also 1.5cm 'shorter' less in diameter , the rim diameter is the same i.e 19"

Yes, verify things with the tire shop.

Just because you have staggered wheels (different size) setup doesn't mean you can't use non-staggered tires (same size).

Good luck!

[powers1]

Originally Posted by omodos

powers and twinspoppa ta for replies, yup have staggered factory setup 132 LA 5 star spokes, at the rear tires are 285/45 r19 which i thought equate to 285mm wide (about 11 inches) and the front 255/50 r19 are 255mm about 10 inches wide, so yup may have to do this, will stick a set of 255/50 tires on the back, they are narrower by about 1inch and lower by 1.25 cm but as long as the garage guys dont say they will pop off and also throw off my sensors due to ride height etc then i will go for them as i will then be able to rotate em all way round(if they are not unidirectional that is )

Omodos,
The 255/50 is NOT lower than the 285/45!Its the same diametre,so it has no effect on you speedo reading or throw off your sensors,so you will be alright.
Just try fitting one and see for yourself,ride the car and you will know whether its ok or not?
The 255 are narrower by 30mm ,but will only be 15mm on either side...nothing like seeing them fitted.
You remember those early VW Golfs where guys used to fot 9" wheels with 205 tyres,,,,now this is radical,with what you are trying to do ,its much more sensible.Lets us know what you think and what the tyre place says.

[omodos]

thanks for all the replies, well the tire guy told me it is not a good idea to fit 255mm wide tyre on a rim size that currently takes 285mm, he was being honest as was not in his interest to lose out on the sale of 255/50 tires yet he still said not to put the 255/50 on, you are right the 285mm and 255mm tire are only out by 30mm....and i was sure the 255/50 meant the aspect ratio i.e the 50 represents the height of the tire i.e 50% of width 127.5mm....anyway just to get an idea of how sensitive the sensors are, i had the guy swap the alloy/wheels round on the same axle, and when i started the car got the sensor exclamation symbol on the dash...reset this and now fine, i guess you are right if i find for example 275/45 tires they will fit fine.....again thanks for all replies

[powers1]

Originally Posted by omodos

thanks for all the replies, well the tire guy told me it is not a good idea to fit 255mm wide tyre on a rim size that currently takes 285mm, he was being honest as was not in his interest to lose out on the sale of 255/50 tires yet he still said not to put the 255/50 on, you are right the 285mm and 255mm tire are only out by 30mm....and i was sure the 255/50 meant the aspect ratio i.e the 50 represents the height of the tire i.e 50% of width 127.5mm....anyway just to get an idea of how sensitive the sensors are, i had the guy swap the alloy/wheels round on the same axle, and when i started the car got the sensor exclamation symbol on the dash...reset this and now fine, i guess you are right if i find for example 275/45 tires they will fit fine.....again thanks for all replies

Well,its a shame the tyre place didnt want to fit,because I just did this on my old 19" and its fine!
Also there is a member here running 255/50 all round and it seems fine ,although it defeats the whole staggered look .
http://www.xoutpost.com/bmw-sav-foru...gered-fit.html

Bit weird that you had sensors error in fitting the 285/45 and 10" wheel in the front.There are members running 285/45 and 315/35 (this is 20") all round ,without sensor error.

[omodos]

mr.powers nope you didn't catch my point, i rotated my wheels side to side at rear, didnt take them up front, also tire guy said installing 255/50 tires on the the existing alloys that have 285/45 tires on them was not going to work..they will fit but as per previous posts i will be fitting a tire that is 30mm narrower than the current one, so not sure how it will stretch or if it will stretch or will just leave gap between the edge of the tire and alloy lip....hmmm hmmm

[TwinsPoppa]

Originally Posted by omodos

mr.powers nope you didn't catch my point, i rotated my wheels side to side at rear, didnt take them up front, also tire guy said installing 255/50 tires on the the existing alloys that have 285/45 tires on them was not going to work..they will fit but as per previous posts i will be fitting a tire that is 30mm narrower than the current one, so not sure how it will stretch or if it will stretch or will just leave gap between the edge of the tire and alloy lip....hmmm hmmm

Like I said below. 255 is too small of a tire for a 10" wide rim.

Originally Posted by TwinsPoppa

Regardless, if you want to use 255/50-19 tires, the max recommended wheel width is 9" - so 10" is too wide.

However, If you want to be able to use your existing staggered setup with the SAME tires front & back - you can use 275/45-19 safely.

275/45-19s can be mounted all the way up to 10.5" wide rims.

If you want to keep your existing wheels, and want to use the same size tires all around, use 275/45-19.

Also, strange that swapping side-to-side at the rear caused the idiot light to go off. I wouldn't think that would cause any problems as its the same wheels and tires. Usually the light comes on because of low pressure in a tire or difference in tire diameter (like due to wear).

[omodos]

okee cokee again thanks I will make a note of that for future ref, if i cant get hold of 285/45's for rear i will look for 275/45 although rear will sit 5cm lower at back compared to size 285/45 now

[TwinsPoppa]

Originally Posted by omodos

okee cokee again thanks I will make a note of that for future ref, if i cant get hold of 285/45's for rear i will look for 275/45 although rear will sit 5cm lower at back compared to size 285/45 now

Lower is okay and the speedo difference is very small. The important thing to keep in mind is have the same tire diameter (not width) at front and rear. Good Luck!

[omodos]

Originally Posted by TwinsPoppa

Lower is okay and the speedo difference is very small. The important thing to keep in mind is have the same tire diameter (not width) at front and rear. Good Luck!

ah ok thanks again so when we say tire diameter we in essence talking about the inner diameter i.e needs to be e.g 275/45 r19 the r19 being the diameter you refer to......