2004 LS 430- Brand new Owner! Wow!
02-17-10, 04:32 PM
#32
Lexus Champion
The only question I have is whether or not there is reason to be concerned about speedometer error because of the change in wheel size.
The 17 inch 04 wheels had P225/55R17 tires (reference Lexus OEM specs). These tires have an overall diameter of 26.7", or 780 Revs Per Mile (ref tirerack.com).
The 18 inch 04 wheels had P245/45R18 tires (reference Lexus OEM specs). These tires have an overall diameter of 26.8", or 777 Revs Per Mile (ref tirerack.com).
The difference, while slight, is 0.38%. The question then becomes whether Lexus recalibrated the speedometer on the car with 18" wheels. Or did they just accept the small error in the speedometer This means that a car with 17" wheels would read 60 mph while the same car with 18" wheels would read 59.77 mph. Conversely, if they recalibrated the speedometer for the 18" wheels and they were then replaced with 17" wheels, then the car would read 60.23 mph.
More important might be the impact on true car mileage. The car with 18" wheels that were changed to 17" wheels would register 100,000 miles when it had actually only traveled 96,200 miles.
Does anybody know how Lexus handled the 18" wheel option regarding accuracy of the speedometer. Or is this error considered to be so low that nobody bothers to be concerned with it? Or am I just a retired engineer with nothing better to do? LOL.
The 17 inch 04 wheels had P225/55R17 tires (reference Lexus OEM specs). These tires have an overall diameter of 26.7", or 780 Revs Per Mile (ref tirerack.com).
The 18 inch 04 wheels had P245/45R18 tires (reference Lexus OEM specs). These tires have an overall diameter of 26.8", or 777 Revs Per Mile (ref tirerack.com).
The difference, while slight, is 0.38%. The question then becomes whether Lexus recalibrated the speedometer on the car with 18" wheels. Or did they just accept the small error in the speedometer This means that a car with 17" wheels would read 60 mph while the same car with 18" wheels would read 59.77 mph. Conversely, if they recalibrated the speedometer for the 18" wheels and they were then replaced with 17" wheels, then the car would read 60.23 mph.
More important might be the impact on true car mileage. The car with 18" wheels that were changed to 17" wheels would register 100,000 miles when it had actually only traveled 96,200 miles.
Does anybody know how Lexus handled the 18" wheel option regarding accuracy of the speedometer. Or is this error considered to be so low that nobody bothers to be concerned with it? Or am I just a retired engineer with nothing better to do? LOL.
Last edited by jayclapp; 02-17-10 at 04:51 PM.
02-17-10, 04:50 PM
#33
Recovering Lexus Addict
02-17-10, 06:34 PM
#34
The only question I have is whether or not there is reason to be concerned about speedometer error because of the change in wheel size.
The 17 inch 04 wheels had P225/55R17 tires (reference Lexus OEM specs). These tires have an overall diameter of 26.7", or 780 Revs Per Mile (ref tirerack.com).
The 18 inch 04 wheels had P245/45R18 tires (reference Lexus OEM specs). These tires have an overall diameter of 26.8", or 777 Revs Per Mile (ref tirerack.com).
The difference, while slight, is 0.38%. The question then becomes whether Lexus recalibrated the speedometer on the car with 18" wheels. Or did they just accept the small error in the speedometer This means that a car with 17" wheels would read 60 mph while the same car with 18" wheels would read 59.77 mph. Conversely, if they recalibrated the speedometer for the 18" wheels and they were then replaced with 17" wheels, then the car would read 60.23 mph.
More important might be the impact on true car mileage. The car with 18" wheels that were changed to 17" wheels would register 100,000 miles when it had actually only traveled 96,200 miles.
Does anybody know how Lexus handled the 18" wheel option regarding accuracy of the speedometer. Or is this error considered to be so low that nobody bothers to be concerned with it? Or am I just a retired engineer with nothing better to do? LOL.
The 17 inch 04 wheels had P225/55R17 tires (reference Lexus OEM specs). These tires have an overall diameter of 26.7", or 780 Revs Per Mile (ref tirerack.com).
The 18 inch 04 wheels had P245/45R18 tires (reference Lexus OEM specs). These tires have an overall diameter of 26.8", or 777 Revs Per Mile (ref tirerack.com).
The difference, while slight, is 0.38%. The question then becomes whether Lexus recalibrated the speedometer on the car with 18" wheels. Or did they just accept the small error in the speedometer This means that a car with 17" wheels would read 60 mph while the same car with 18" wheels would read 59.77 mph. Conversely, if they recalibrated the speedometer for the 18" wheels and they were then replaced with 17" wheels, then the car would read 60.23 mph.
More important might be the impact on true car mileage. The car with 18" wheels that were changed to 17" wheels would register 100,000 miles when it had actually only traveled 96,200 miles.
Does anybody know how Lexus handled the 18" wheel option regarding accuracy of the speedometer. Or is this error considered to be so low that nobody bothers to be concerned with it? Or am I just a retired engineer with nothing better to do? LOL.
LOL I kept looking for a or SOMETHING 'cause I know you can't be serious about that. .38%??? 380 miles on 100,000??? Good one!!! 
Last edited by I6turbo; 02-17-10 at 06:41 PM.
Thread
Thread Starter
Forum
Replies
Last Post
ldmf
LS - 4th Gen (2007-2017)
24
06-13-18 06:08 AM
mdebolt
LS - 3rd Gen (2001-2006)
4
03-05-07 11:05 PM
ted920
LS - 3rd Gen (2001-2006)
12
10-25-05 10:33 PM
