Wider rear wheels on X3 w/o sport pkg

[byngsk]

Hi,

I'm thinking of replacing the stock wheels (23555R17) on
my 2006 X3 with 8x18 (23550R18) in the front and 9x18
(25545R18) in the rear.

Now, would this work on the X3 w/o sport pkg ? Will there
be any performance issue or gain (besides the looks) ?

Thanks,

Byungsuk

[simoncpw]

I did mine in the same way, no noticable difference in performance, but I do feel the ride a little more with the lower profile tires.

[byngsk]

Originally Posted by simoncpw

I did mine in the same way, no noticable difference in performance, but I do feel the ride a little more with the lower profile tires.

Thanks for your reply. btw, how about the fuel efficiency ? Will it get worse ?

[818Guy]

Probably not.

BTW, your fronts will be 0.3% too slow. When your speedo reads 60mph, you'll be traveling 60.2mph.

With your rears, you will be 0.5% too fast. When your speeo reads 60mph, you'll be traveling 59.7mph.

http://www.miata.net/garage/tirecalc.html

Just make sure you have an acceptable offset with new wheels.

[drex]

lol how can the speed of the vehicle read different at both axles?

I understand your point; however, the overall speed will be an average of both, resulting in 60.05 mph. He would never notice!

[motordavid]

Originally Posted by drex

lol how can the speed of the vehicle read different at both axles?

I understand your point; however, the overall speed will be an average of both, resulting in 60.05 mph. He would never notice!

And, this is on a Brand that admits its speedos are quite optimistic!

Like the old Chicago song, paraphrased: "Does anyone really know what
their real speed is?!"
BR,md

[byngsk]

Originally Posted by 818Guy

Probably not.

BTW, your fronts will be 0.3% too slow. When your speedo reads 60mph, you'll be traveling 60.2mph.

With your rears, you will be 0.5% too fast. When your speeo reads 60mph, you'll be traveling 59.7mph.

http://www.miata.net/garage/tirecalc.html

Just make sure you have an acceptable offset with new wheels.

Guys,

Thanks for your replies. I get your point. So, basically the speedo reading could be slightly different but negligible.

Now, how about the offset ? I want to use 192M (235 and 255) wheels that normally come with SP. Do I still have to worry about the offset ?

[simoncpw]

Originally Posted by byngsk

Thanks for your reply. btw, how about the fuel efficiency ? Will it get worse ?

Not that I'm awared of, but I've had the car only for a month when changing to the current rims and tyres.

On the speedo's reading differences, it shouldn't be any issues. These are exactly the same sizes as what BMW puts on the 18" rims for X3.

[MysticBlueX3]

Originally Posted by byngsk

Hi,

I'm thinking of replacing the stock wheels (23555R17) on
my 2006 X3 with 8x18 (23550R18) in the front and 9x18
(25545R18) in the rear.

Now, would this work on the X3 w/o sport pkg ? Will there
be any performance issue or gain (besides the looks) ?

Thanks,

Byungsuk

Thats what I have on my car now. 235/50-18 front, 255/45-18 rear. It's the OEM premium sport pkg. setup.

[byngsk]

Originally Posted by simoncpw

Not that I'm awared of, but I've had the car only for a month when changing to the current rims and tyres.

On the speedo's reading differences, it shouldn't be any issues. These are exactly the same sizes as what BMW puts on the 18" rims for X3.

Thanks!! Very helpful illustration.