Tyre size for 18" rim
- Thread starter Phlipper1
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Most people seem to have fitted 225/40's, but surely on a wider rim you'd move to a wider tyre?
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An 18" rim doesn't necessarily mean that the rim is wider, the width of the rim is quoted in inches and specified as a J figure, for example 8J. The quoted figure is the distance between the fitting faces of the inner and outer beads.
Most people seem to have fitted 225/40's, but surely on a wider rim you'd move to a wider tyre?
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An 18" rim doesn't necessarily mean that the rim is wider, the width of the rim is quoted in inches and specified as a J figure, for example 8J. The quoted figure is the distance between the fitting faces of the inner and outer beads.
Assuming that the standard s3 rim is 17 x 7.5 the 18" rim maybe 8 or 8.5 wide (i.e. RS4 rim)? You would have to try and maintain the original circumference of both wheel + tyre so as not alter the speedo settings. What sort of profile would I need if I went to 235 or 245. I'm guessing 235/40 for 8" and 245/35 for 8.5.
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Assuming that the standard s3 rim is 17 x 7.5 the 18" rim maybe 8 or 8.5 wide (i.e. RS4 rim)? You would have to try and maintain the original circumference of both wheel + tyre so as not alter the speedo settings.
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absolutely, but maintaining the same rolling radius has nothing to do with the width of the tyre, you just need to make sure you use the correct section tyres.
edit: oops - stand corrected as normal....
Assuming that the standard s3 rim is 17 x 7.5 the 18" rim maybe 8 or 8.5 wide (i.e. RS4 rim)? You would have to try and maintain the original circumference of both wheel + tyre so as not alter the speedo settings.
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absolutely, but maintaining the same rolling radius has nothing to do with the width of the tyre, you just need to make sure you use the correct section tyres.
edit: oops - stand corrected as normal....
AndyMac
Retired from service
Yes, but as you move to a wider tyre the options on tyre size give you a less accurate rolling radius. 225/40/18 gives you the most accurate rolling radius (within 0.5%), if you then move to 235 or 245 widths this moves to 1.7% or 3% respectively unless you're gonna drop down to a 35% profile which gets expensive.
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The profile is quoted as a % proportion of the width so obviously as width increases then profile number decreases.
My factory tyres were 225/40/18's so this yields the optimum rolling radius.
You could fit say 235/35/18's but why would you? I think the tyres are wide enough at 225.
My factory tyres were 225/40/18's so this yields the optimum rolling radius.
You could fit say 235/35/18's but why would you? I think the tyres are wide enough at 225.
AndyMac
Retired from service
Anything up to 8.5/18 I wouldnt go over 225 wide tyres. 9/18 or wider would need wider tyres but you dont need wheels that wide on a 3... unless its just for the looks?? then you get rubbing and handling issues.
Lets just say you were having a play with a Boxter. According to some people the S3 is going to struggle due to the comparative balance and neutrality issues of it's handling (ees_three's comments). A colleague at work has just got a Boxter. I happened to notice the 265/35 19's on the back. So surely physical grip must be a factor.
AndyMac
Retired from service
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Lets just say you were having a play with a Boxter. According to some people the S3 is going to struggle due to the comparative balance and neutrality issues of it's handling (ees_three's comments). A colleague at work has just got a Boxter. I happened to notice the 265/35 19's on the back. So surely physical grip must be a factor.
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Ever seen the size of the tyres on an Elise?
Lets just say you were having a play with a Boxter. According to some people the S3 is going to struggle due to the comparative balance and neutrality issues of it's handling (ees_three's comments). A colleague at work has just got a Boxter. I happened to notice the 265/35 19's on the back. So surely physical grip must be a factor.
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Ever seen the size of the tyres on an Elise?
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Lets just say you were having a play with a Boxter. According to some people the S3 is going to struggle due to the comparative balance and neutrality issues of it's handling (ees_three's comments). A colleague at work has just got a Boxter. I happened to notice the 265/35 19's on the back. So surely physical grip must be a factor.
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The Porker has wider rear wheels to stop it oversteering and spinning. Wider rears on the 3 would cause more understeer I think
Lets just say you were having a play with a Boxter. According to some people the S3 is going to struggle due to the comparative balance and neutrality issues of it's handling (ees_three's comments). A colleague at work has just got a Boxter. I happened to notice the 265/35 19's on the back. So surely physical grip must be a factor.
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The Porker has wider rear wheels to stop it oversteering and spinning. Wider rears on the 3 would cause more understeer I think
