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Old 12-08-2008, 10:54 AM   #6
cucamelsmd15
Scooby Specialist
 
Member#: 122980
Join Date: Aug 2006
Chapter/Region: South East
Location: Raleigh, NC
Vehicle:
2010 F150, 2013 CX-5
92 Miata 15 TTF/PTF/E3

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Quote:
Originally Posted by juanmedina View Post
we have 2 cars they are identical, they have the same power mods, same suspension mods, same everything but wheels and tires.

Car A: has some 18x9.5 wheels that weight 22 lbs and some 245/40/18 tires that weight 27 lbs

Car B: has some 17x8 wheels that weight 14 lbs and some 215/40/17 tires that weight 18 lbs.

**tires are the same brand and compound**

Which will win on Auto cross, how about road racing, and drag?

Idk I know one will more surface contact but the other will have less rotational mass.



Code:
Stock Tire - 215/40R17    
Tire 1 - 245/40R18         

Section Width: 8.46 in 215 mm 
Section Width: 9.64 in 245 mm 
 
Rim Diameter: 17 in 431.8 mm 
Rim Diameter: 18 in 457.2 mm 
 
Rim Width Range: 7 - 8.5 in 
Rim Width Range: 8 - 9.5 in 
 
Overall Diameter: 23.77 in 603.75 mm 
Overall Diameter: 25.71 in 653.03 mm 
 
Sidewall Height: 3.38 in 85.852 mm 
Sidewall Height: 3.85 in 97.79 mm 
 
Radius: 11.88 in 301.75 mm 
Radius: 12.85 in 326.39 mm 
 
Circumference: 74.67 in 1896.6 mm 
Circumference: 80.77 in 2051.5 mm 
 
Revs per Mile: 875.0 
Revs per Mile: 809.0 
 
Actual Speed: 60 mph 100 km/h 
Speedometer1: 55.4 mph 92.4 km/h 
 
Speedometer Difference: - Speedometer Difference: 8.158% too slow 
Diameter Difference: - Diameter Difference: 7.55%
Better driver wins, handsdown.
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