spare wheel doesn't match those fitted

[ceticcross]

Hello from a complete newbie,

Bought a 2003 E320 CDI last night with 18" agm Alloys fitted. When looking for the spare today I noticed it is a 17". I am being stupid in asking would the 17" fit in an emergency get you home situation?
Thanks for any replies

 

[grober]

The rolling radius is what's important. That's the radius of the wheel+tyre. Check the radius of the mounted wheels and the spare. I bet you will find they are the same. This is due the different aspect ratio of the tyres--This means the sidewall height will be different on the 18" and 17" tyres with the 17" being bigger to compensate for its smaller wheel diameter. check out the calculator here. Car Bibles : The Wheel and Tyre Bible Page 2 of 2

 

[x332race]

Is that a 17" "space saver" tyre. ie. is the tyre much narrower than normal?

At the end of the day it is the rolling circumference that is important....ahh...just noticed Grober has replied to this......

 

[Sp!ke]

You may want to check that the wheel bolt lengths are the same for both types of wheel. They probably are the same length but its better knowing that than finding out they are not, the hard way in the pooring rain one day.

 

[Rory]

You may want to check that the wheel bolt lengths are the same for both types of wheel. They probably are the same length but its better knowing that than finding out they are not on the hard way in the pooring rain one day.

They're usually different - mine are in a little plastic case attached to the underneath of the space-saver.

 

[ceticcross]

Thanks to everyone for the replies. It well dark outside now so I cannot check the spare wheel. I think it was the original spare and just not upgraded when the 4 main ones were changed to AMG. I don't think it is a spacesaver but will have a beter look in daylight.
Thanks again

 

[jaymanek]

it doesnt matter that the space saver is 17".. like has been said, the rolling radius will be the same..

Cars that have 18" wheels from factory still have the standard space saver.

 

[ceticcross]

Thanks again to you all . My mind is a bit more at rest now.