Got a set of 14" bbs cross spoke alloys i've just refurbed, so now i need tyres. Currently running 195/65 on 14" bottle tops. Not to keen on the balloon like appearance of these, so was thinking 195/50 possibly?? Not sure how much his would affect gearing/speedometer though? . . . .
Any suggestions?
tyre size?
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hongkongfuey
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bigger wheels? if you had 15" you could have 205/50
as for what you got, 195/50 would give you abit more acceleration, less topend
as for what you got, 195/50 would give you abit more acceleration, less topend
if there wern't people like me,
with cars like mine,
who would you put down to make yourself feel better?
with cars like mine,
who would you put down to make yourself feel better?
If you change the rolling radius from standard, then both your gearing and speedometer will be inaccurate. Of course just dropping down a profile size won't affect it massively but still a difference. As HKF mentioned above if you wish to go wish a lower profile tyre then go up in wheel diameter to compensate 
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Von_Thrash
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It's gotta be the 14" wheels for various reasons - no money for anything else being the main one. I gettit that smaller overall rolling radius means better acceleration, less top end. But would a 15mm reduction in profile really be noticable? Saying that would it even be visually noticable? I plan to lower the car a little which will reduce the arch gap. What does everyone else run on 14" wheels?
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Grrrmachine
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A reduction from 195/65 to 195/50 isn't a reduction of 15mm. The 65 and 50 represent a percentage of the width (195), not a millimeter value.
65% of 195 is 127mm
50% of 195 is 97mm
Then remember that's just the sidewall between the rim and the tread, so that's TWO sidewalls to affect the entire diameter of the wheel. So you're changing the diameter by 60mm, or nearly 2.5", which will definitely be noticeable.
Learn to understand tyres, then think seriously about changing them away from standard.
65% of 195 is 127mm
50% of 195 is 97mm
Then remember that's just the sidewall between the rim and the tread, so that's TWO sidewalls to affect the entire diameter of the wheel. So you're changing the diameter by 60mm, or nearly 2.5", which will definitely be noticeable.
Learn to understand tyres, then think seriously about changing them away from standard.
'89 325i Touring | Touring Resto Thread | In-Dash Screen install
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Grrrmachine
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Sorry, I just wanted to explain that a profile reduction doesn't "just" mean 15mm... it counts twice.
Still, it works out at nearly 10% difference to the wheel; that's pretty significant.
Still, it works out at nearly 10% difference to the wheel; that's pretty significant.
'89 325i Touring | Touring Resto Thread | In-Dash Screen install
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Von_Thrash
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InformativeGrrrmachine wrote:A reduction from 195/65 to 195/50 isn't a reduction of 15mm. The 65 and 50 represent a percentage of the width (195), not a millimeter value.
65% of 195 is 127mm
50% of 195 is 97mm
Then remember that's just the sidewall between the rim and the tread, so that's TWO sidewalls to affect the entire diameter of the wheel. So you're changing the diameter by 60mm, or nearly 2.5", which will definitely be noticeable.
Learn to understand tyres, then think seriously about changing them away from standard.
thankyou. I know im not the only one who thought the sidewall figue was a measurement rather than a ratio.
indeed, tyre sizes are a really weird one. prbably the only time you'll see metric, imperial, and a percentage figure when describing one product 
for tyre sizes, try this site:
http://www.tyresave.co.uk/tyresize.html
it tells you the percentage difference in rolling radius.
HTH
for tyre sizes, try this site:
http://www.tyresave.co.uk/tyresize.html
it tells you the percentage difference in rolling radius.
HTH
no no, well pointed out - it's fact that people aren't aware that the aspect ratio (profile) is a percentage of the width..Grrrmachine wrote:Sorry, I just wanted to explain that a profile reduction doesn't "just" mean 15mm... it counts twice.
Still, it works out at nearly 10% difference to the wheel; that's pretty significant.
If you know your gear & diff ratios, this is what you want to use to calculate the differences in road speed through the gears
it doesn't account for the effect on acceleration, but the effect of tire size is evident through the rev range
http://www.unixnerd.demon.co.uk/revs.html
will bookmark that one 
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Grrrmachine
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If it helps, I seem to remember that the standard tyre is actually a 185/65 rather than a 195/65. If that's true, then you can go down to 195/60 or a 205/60 (for a 1% difference either way), depending on availability and whether they'll fit the rims.
If it's not 185/65, you're screwed
If it's not 185/65, you're screwed
'89 325i Touring | Touring Resto Thread | In-Dash Screen install
