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Discussion Starter · #1 ·
Hi all

I would like to increase rear-end grip on my 2004 e46 320cd.

It currently has front and rear: 205/50W17 on standard rims (whatever width they are?). Runflats.

Questions:

Would adding a larger width tyre to the rears improve grip?
..if yes, is it possible to do this keeping the existing rims?
..if yes, what size would you recommend I use? / max size?
..once fitted, are the pressures for the new tyres going to be the same as those detailed on the door frame? (It isn't clear if BMW supply the larger width tyres on larger width rims - I assume it makes a slight difference?)

..if you think the above is pure folly and have any other (cost effective) ways of achieving my objective, please let me know - I was looking at replaceing the trailing arm bushes so anyone with info on how this effects handling I'd also love to hear from you.

TIA for any assistance
Jamie
 

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The tyre measurements you currently have mean...

205 (width in mm)/50 (aspect ratio, in your case its 50% of 205 = 102.5mm tyre wall), 17 (width of wheel rim in inches)

According to the michelin website, on a 320CD 2003> you can use the following tyres

205/50/17 93 W REINF.
225/45/17 91 W

Front 225/45/17 91 Y
Rear 245/40/17 91 Y

according to that, if you want improved grip you can fit the latter two on the car which should improve grip but the wider front might make the car tramline slightly (which is when the steering reacts much more to the contours of the road)

upgrading to polyeurethane bushes may improve the handing, but uprated anti roll bars and strut braces can tighten up the chassis and make a lot of difference.

best way is no doubt to get a good set of tyres, as these are the only contact between the car and the road though.

hope that helps
 

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Discussion Starter · #3 ·
Thanks Badj, if 225 is 20mm wider than a 205 I guess it could be just enough. Not many cars (certainly not in this power bracket) go to a difference of 205/245 F/R so that would seem to be the right way forward...

Cheers
 

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no problem. some people have been known to squeeze 265 on them, that info came direct from michelin so should be spot on. wouldnt like the tyre bill however!
 
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