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Discussion Starter #1
I know this isn't in the tyre section but I need some specific advice for my Cooper D.

It's currently on 16" Goodyear standard run-flat tyres but I want to upgrade to 17's now.

I've got some Bullet alloys waiting for tyres to go on but I have no idea what to go for in terms of size... 205/45/17, 215/45/17 or 215/40/17?

Has anyone changed to non-runflats on their Cooper D and if so, what tyre and size did you go for etc?

Please help :D
 

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Discussion Starter #3
Ive got 215/45/R17 but the standard is 205/45/R17...
I was seriouslyt considering that size but three different tyre places have warned me against it so now I'm thinking of going for 215/40/17 :rolleyes:

What tyres have you got and what do you think of 'em?
 

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The closest match to the original 195/55R16 is 215/45R17 size. Difference is 0.71% which is well within the 2% difference recommended for DSC.
 

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Thanks... I was beginning to wory that my tire guy had set me up with the wrong wheels... But howcome are the original Mini rims then delievered on the 205/40/17 wheels??
 

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Thanks... I was beginning to wory that my tire guy had set me up with the wrong wheels... But howcome are the original Mini rims then delievered on the 205/40/17 wheels??
AIRC the brochure states that most 17" wheels come with the 215/45R17 combo and I seem to remember one set of 17" wheels come with 225/45R17 tyres. Which 17" wheel comes with 205/40R17 tyre fitted? The 205/40R17 is 0.74% smaller so again within 2%. It would be interesting to see the ET offsets for all these wheels.
 

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Discussion Starter #13
The standard tyres on MINIs are 205/45/17. I went to the MINI garage near me and at least four MINIs had that size.

215/45/17 is apparently completely wrong... it should be 215/40/17?
 

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Discussion Starter #15
With the MINIs there's a standard 17" tyre size of 205/45 so to keep the rolling resistance etc the same, you have to sacrifice one part ofthe tyre size for another... i.e. - 215/40.

Plenty of people on here seem to have the 215/45 so I'm sure in reality it's fine but MINI and the 3x tyre companies I spoke to immediately said it's too big for the MINI.

I'm only forwarding what I've been told :D
 

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With the MINIs there's a standard 17" tyre size of 205/45 so to keep the rolling resistance etc the same, you have to sacrifice one part ofthe tyre size for another... i.e. - 215/40.

Plenty of people on here seem to have the 215/45 so I'm sure in reality it's fine but MINI and the 3x tyre companies I spoke to immediately said it's too big for the MINI.

I'm only forwarding what I've been told :D
There are a number of factors to take into account when changing tyres/wheels for different sizes but in general rolling resistance is not one of them. The key factors to take into account are :
- tyre circumference i.e. is the new tyre circumference the same size as the original tyre. BMW recommend that in order not to interfere with DSC/ABS and also to keep your speedo reasonably accurate that the new tyre is within 2%.
- tyre width. The width of the tyre needs to be taken into account as if it is too wide then it could foul the suspension and/or wheelaraches. Tyre width needs to be considered in combination with the offset (ET) of the new wheels. Some wheels have offsets designed to allow the fitment of wider tyres on the Mini. This must be the case as the R108 wheel listed in the brochure (page90) comes fitted with a 225/45R17 tyre which must fit on the Mini.
- brake caliper/disc clearance. Not an issue here but if you have fitted bigger discs and claipers then you need to ensure that the new wheel does not foul on your uprated discs/calipers.

So taking all the above into account and using the tyre size calculator link that I posted earlier you will see that the 215/45R17 size is the closest match to the OEM 195/55R16 tyre with a difference of 0.71%. The next closest is the 205/45R17 with a difference of -0.74%.
So from a pure tyre circumference perspective the 215/45R17 tyre is the closest match. Obviously one does need to consider the offset (ET) of the wheel that tyres are going on but it is unlikely that a 215 width would give problems on a OEM 17" wheel compared to a 205 width tyre.
 

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Discussion Starter #18
There are a number of factors to take into account when changing tyres/wheels for different sizes but in general rolling resistance is not one of them. The key factors to take into account are :
- tyre circumference i.e. is the new tyre circumference the same size as the original tyre. BMW recommend that in order not to interfere with DSC/ABS and also to keep your speedo reasonably accurate that the new tyre is within 2%.
- tyre width. The width of the tyre needs to be taken into account as if it is too wide then it could foul the suspension and/or wheelaraches. Tyre width needs to be considered in combination with the offset (ET) of the new wheels. Some wheels have offsets designed to allow the fitment of wider tyres on the Mini. This must be the case as the R108 wheel listed in the brochure (page90) comes fitted with a 225/45R17 tyre which must fit on the Mini.
- brake caliper/disc clearance. Not an issue here but if you have fitted bigger discs and claipers then you need to ensure that the new wheel does not foul on your uprated discs/calipers.

So taking all the above into account and using the tyre size calculator link that I posted earlier you will see that the 215/45R17 size is the closest match to the OEM 195/55R16 tyre with a difference of 0.71%. The next closest is the 205/45R17 with a difference of -0.74%.
So from a pure tyre circumference perspective the 215/45R17 tyre is the closest match. Obviously one does need to consider the offset (ET) of the wheel that tyres are going on but it is unlikely that a 215 width would give problems on a OEM 17" wheel compared to a 205 width tyre.
Well now I'm completely baffled... I don't know whether to go for 215/40 or 215/45:rolleyes:
 

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Discussion Starter #19
By the way, I'm fitting the tyres to MINI Bullet alloys if that helps you to help me scillyisles? :D
 
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