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Author Topic: Wheels and tyres question - going from 16 to 17 wheels  (Read 1424 times)
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Lindsay
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« on: 29 March, 2011, 07:03:19 AM »

Morning all, not one for a Lancia per se but.... I am wanting to change the wheels on my R129 SL Mercedes from the original 8 hole alloys which are 16", tyres 225/55/16s to a set of 17" wheels which I have.  They currently have 245/45/17 tyres on them. My reckoning is to keep the ratio correct, the 17"s should ideally have 235/45/17s. Is this correct?

Also, if I run it with the 245s will it make much difference - aside from changing the gearing slightly and making the instruments read slightly over/under?

Lastly, if I change the tyres in pairs, would I be ok to change the fronts to 235 and keep the rears at 245 until they need new tyres?

I would go on the Mercedes forum but I can't be doing with Mercedes folk!!
thanks
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Neil
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« Reply #1 on: 29 March, 2011, 09:30:57 AM »

Lindsay,

I just looked up the tyre/wheel sizes, looks like you need 245/45 x 17 not 235/45 x17 - 245/45 x 17 has overall tyre diameter of 652mm and the original tyre size was 654mm, so not much in it, if you went for 235/45 x 17 it would be 643mm smaller overall wheel and tyre so the speedo would over read.   I guess you could mix sizes front to to back as long as they are same per axle and four wheel drive  Cheesy

Try this link: http://www.alloywheelworld.co.uk/page.php/tyrecalc.html
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Neil   
386

1973 Fulvia S2 1.3
Lindsay
Guest
« Reply #2 on: 29 March, 2011, 12:07:42 PM »

Lindsay,

I just looked up the tyre/wheel sizes, looks like you need 245/45 x 17 not 235/45 x17 - 245/45 x 17 has overall tyre diameter of 652mm and the original tyre size was 654mm, so not much in it, if you went for 235/45 x 17 it would be 643mm smaller overall wheel and tyre so the speedo would over read.   I guess you could mix sizes front to to back as long as they are same per axle and four wheel drive  Cheesy

Try this link: http://www.alloywheelworld.co.uk/page.php/tyrecalc.html


Hi Neil, thanks for the reply. Too complicated for me! But your explanation is clear and makes sense so its good enough for me!
cheers
Lindsay
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