Speedometer Calibration!? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

AZOOZ_95 · 05-02-2013, 05:02 AM

Hey guys, I have question since im a noob

with this stuff. I heard that if you put larger tires, or rims on a car you need to calibrate, what does that mean, and how do u do it?

Another question I have is how would you Keep it closest to the stocks, so you would need to calibrate?

I really want understand this

Thanks

n2oinferno · 05-02-2013, 08:32 AM

You won't need to calibrate it if you keep the overall outside diameter of the tire the same.
Use the calculator found at this link to input the stock tire size (215/45 17) and then input the tire size that you're looking at. It will tell you what the difference in speed is. Get as close as possible and it's pretty negligible.

http://www.miata.net/garage/tirecalc.html

AZOOZ_95 · 05-03-2013, 01:35 AM

Quote:

Originally Posted by n2oinferno

You won't need to calibrate it if you keep the overall outside diameter of the tire the same.
Use the calculator found at this link to input the stock tire size (215/45 17) and then input the tire size that you're looking at. It will tell you what the difference in speed is. Get as close as possible and it's pretty negligible.

http://www.miata.net/garage/tirecalc.html

Thanks! My next question.... What if it was a big difference, how would u actually calibrate it? And would it cost a lot?

n2oinferno · 05-03-2013, 08:43 AM

Couldn't tell you. I've worked on a few cars in the past with mechanical speedometers, so you could swap a gear out to get it right. I'm betting these are all electronic though and figured by vehicle speed sensors.

IMO, stick to the "correct" tire sizes; an extremely oversized setup is going to look silly anyway.

AZOOZ_95 · 05-03-2013, 08:50 AM

Quote:

Originally Posted by n2oinferno

Couldn't tell you. I've worked on a few cars in the past with mechanical speedometers, so you could swap a gear out to get it right. I'm betting these are all electronic though and figured by vehicle speed sensors.

IMO, stick to the "correct" tire sizes; an extremely oversized setup is going to look silly anyway.

THANKS

wparsons · 05-03-2013, 11:57 AM

Just keep it as close to stock diameter as possible, not worth it to bother with calibrating it - especially if you have winter wheels.

My 225/45/17's are 0.3" taller than stock, but based on GPS the displayed speed is still dead on compared to stock tires.

Kdej1 · 05-04-2013, 08:07 PM

are the fr-s speed sensors a gear or magnetic? Alot of newer cars have been using magnetic ones, and in that case if you ever needed to re-calibrate it you can buy a speed healer.. I have one on my civic.. Pretty easy to install, was three wires iirr..
http://www.dakotadigital.com/index.c...rod/prd126.htm

install it, hop on freeway, have passenger adjust it by pressing up/down buttons..

05-02-2013, 05:02 AM	#1
AZOOZ_95 Middle Eastern 86 Join Date: Mar 2013 Drives: RED GT86 Location: Saudi Arabia Posts: 162 Thanks: 601 Thanked 17 Times in 13 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Speedometer Calibration!? Hey guys, I have question since im a noob with this stuff. I heard that if you put larger tires, or rims on a car you need to calibrate, what does that mean, and how do u do it? Another question I have is how would you Keep it closest to the stocks, so you would need to calibrate? I really want understand this Thanks

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05-02-2013, 08:32 AM	#2
n2oinferno Praise Helix! Join Date: Jan 2011 Drives: Accord 2.0T, Silverado Location: Upstate SC Posts: 2,859 Thanks: 428 Thanked 2,208 Times in 1,072 Posts Mentioned: 11 Post(s) Tagged: 1 Thread(s)	You won't need to calibrate it if you keep the overall outside diameter of the tire the same. Use the calculator found at this link to input the stock tire size (215/45 17) and then input the tire size that you're looking at. It will tell you what the difference in speed is. Get as close as possible and it's pretty negligible. http://www.miata.net/garage/tirecalc.html

05-03-2013, 08:43 AM	#4
n2oinferno Praise Helix! Join Date: Jan 2011 Drives: Accord 2.0T, Silverado Location: Upstate SC Posts: 2,859 Thanks: 428 Thanked 2,208 Times in 1,072 Posts Mentioned: 11 Post(s) Tagged: 1 Thread(s)	Couldn't tell you. I've worked on a few cars in the past with mechanical speedometers, so you could swap a gear out to get it right. I'm betting these are all electronic though and figured by vehicle speed sensors. IMO, stick to the "correct" tire sizes; an extremely oversized setup is going to look silly anyway.

05-04-2013, 08:07 PM	#7
Kdej1 Colten Drew Join Date: Mar 2013 Drives: '13 Fr-s // '95 Civic // '09 Vette Location: Phx, AZ Posts: 52 Thanks: 3 Thanked 26 Times in 10 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	are the fr-s speed sensors a gear or magnetic? Alot of newer cars have been using magnetic ones, and in that case if you ever needed to re-calibrate it you can buy a speed healer.. I have one on my civic.. Pretty easy to install, was three wires iirr.. http://www.dakotadigital.com/index.c...rod/prd126.htm install it, hop on freeway, have passenger adjust it by pressing up/down buttons..

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