Changin rim size lowers et?
5/24/11, 07:24 PM
#1
Bullitt Member
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Changin rim size lowers et?
Im having the idea that changing tire size gives the same effect then changin gear ratio,what rim size with what tire size would give the best result for drag racing in 1/8 mile?and to what gear ratio would that size be compared to?
5/25/11, 07:30 AM
#2
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Join Date: December 15, 2010
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The Theory behind your thought is correct in general, You can actually figure this out with some pretty basic math... Ex. If you want to simulate going to a "lower" gear set (swapping out 3.73 with 4.10)
- Take the Gear ratio you have and simply divide it into your new ratio.This will give you a percentage. ex-( 3.73/4.10)=.91 (rounded to the third digit is more than sufficient)
- Next take the Diameter tire you are running and multiply it by the percentage you have. ex- (28.0" x .91)= 25.5"
So now in theory you have a 25.5" tire that simulates 4.10 gears
Now the problems with this practice.
-If you are looking for a large gain in (gear ratio) you will not achieve it by tire size, You cannot simulate a 3.27 with 4.30s, The differance in tire size would be way to dramatic to even be considered.
-If you are going from a larger tire diameter to a smaller diameter you will also be losing contact patch area, Not a good thing for those 60' times
-Taller tires have a dynamic effect as they are traveling at high speeds (they actually get a little taller. ( just watch a Top Fuel Dragster during a burnout) Of course this will be an exagerated picture but you get the idea..
-So to make a long story short, This is something that will only work on a small scale, If you are going through the traps a few hundered RPMS short of peak RPM than this will benefit you. Or vice versa, you can take some RPM out by going with a larger diameter... Hope this Helps!
- Take the Gear ratio you have and simply divide it into your new ratio.This will give you a percentage. ex-( 3.73/4.10)=.91 (rounded to the third digit is more than sufficient)
- Next take the Diameter tire you are running and multiply it by the percentage you have. ex- (28.0" x .91)= 25.5"
So now in theory you have a 25.5" tire that simulates 4.10 gears
Now the problems with this practice.
-If you are looking for a large gain in (gear ratio) you will not achieve it by tire size, You cannot simulate a 3.27 with 4.30s, The differance in tire size would be way to dramatic to even be considered.
-If you are going from a larger tire diameter to a smaller diameter you will also be losing contact patch area, Not a good thing for those 60' times
-Taller tires have a dynamic effect as they are traveling at high speeds (they actually get a little taller. ( just watch a Top Fuel Dragster during a burnout) Of course this will be an exagerated picture but you get the idea..
-So to make a long story short, This is something that will only work on a small scale, If you are going through the traps a few hundered RPMS short of peak RPM than this will benefit you. Or vice versa, you can take some RPM out by going with a larger diameter... Hope this Helps!