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Two questions surrounding me wanting to swap out my 06 S Tires and Rims for OR Tires and Rims.

1. Will my speedometer be affected (e.g. wont report speed correctly) due to the increase in diameter from 16" to 17" rim and the tire size differences

2. Will I have enough clearance to make this happen correctly? Do I have to put on a lift kit?
 

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S wheels and OR wheels are both 16".

1.- Wheel diameter has no direct effect on speedometer. Only Overall Tire Diameter. Like 265/75/16 is very similar to 265/70/17...

2.- Again clearance is only a function of tire diameter. You can fit 32" without any problems on a stock X.

:geek:

PS: Play with this tire size calculator
 

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Discussion Starter #3
Thanks for the reply, sorry someone told me the OR rims were 17's. thats good, I guess the SE 4 spoke rims are 17's then
 

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speedo will read 3.3% fast.

so you go 58mph, speedo reads 60mph.
 

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Rastaman said:
S wheels and OR wheels are both 16".

1.- Wheel diameter has no direct effect on speedometer. Only Overall Tire Diameter. Like 265/75/16 is very similar to 265/70/17...
Wheel diameter DOES have a direct effect on the speedo. Increasing wheel diameter w/o speedo correction results in a false low reading (ie: your actually traveling faster than speedo shows. Assuming you keep the profile of the new tire the same as the stock tire.). Play with the calculator you mentioned and you will see. Remember: Cirumference= Pi X Diameter. Speedos are based on wheel revolution. If the circumference is increased by either a larger diameter wheel or taller tire, then each roll of the wheel covers a greater distance. This is assuming that that if you increase your wheel diameter, you don't decrease the profile of the tire.
 

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buxwheat said:
Rastaman said:
S wheels and OR wheels are both 16".

1.- Wheel diameter has no direct effect on speedometer. Only Overall Tire Diameter. Like 265/75/16 is very similar to 265/70/17...
Wheel diameter DOES have a direct effect on the speedo. Increasing wheel diameter w/o speedo correction results in a false low reading (ie: your actually traveling faster than speedo shows. Assuming you keep the profile of the new tire the same as the stock tire.). Play with the calculator you mentioned and you will see. Remember: Cirumference= Pi X Diameter. Speedos are based on wheel revolution. If the circumference is increased by either a larger diameter wheel or taller tire, then each roll of the wheel covers a greater distance. This is assuming that that if you increase your wheel diameter, you don't decrease the profile of the tire.

thats why he said "Only Overall Tire Diameter."
 

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Physical wheel has nothing to do with speedometer error. It is the tires Outside diameter that affects the speedo. The contact area, if you have a 16" wheel with a 32" tire it will be the same as a 20" wheel with a 32" tire given that the tires acctual O.D. is 32" and tire width is the same.
 

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buxwheat said:
[
Wheel diameter DOES have a direct effect on the speedo.
Wheel--no

Tire--yes

Me thinks the avatar serves as a hint to the reason for the confusion. Just step away from the bong... :geek:
 

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I think some folks missed my point. True, the tire height and hence the diameter of the wheel/tire assembly determines the circumference. So indeed a 32 inch tire has the same diameter no matter what diameter rim it's mounted on. I was just trying to say if you get a larger rim and fit a tire on it with the same sidewall-to-sidewall width and aspect ratio as that mounted on a smaller rim, the resulting diameter would be greater. A tire's theoretical height in inches is calculated as follows:

Height = (Width x (Ratio/100) x .03937 x 2) + Rim Diameter

The width multiplied by the aspect ratio over 100 gives the height in millimeters, multiplying by .03937 converts to inches, and doubling this accounts for the fact that there's tire at the bottom and the top of the rim.

Didn't mean to say that the wheel diameter was the only variable in determining height, but by keeping the width and aspect ratio constant, height would vary as a function of rim diameter.
 

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his speedo....will now be corrected with the OR size tires. a couple other people have found that their speedo no longer is 'slow' once they switch from 265/70 to the 265/75R16 (once again, liability raises its ugly head)
 

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lol my 2006 GTI was the exact opposite. most of the speedos ran up to 10% faster. This Nissan speedo is super accurate to me now.
 
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