195-50-15 or 195-55-15??
- Thread starter jsp413
- Start date
endo617
Rattle Can Technician
for "15 wheels i run 205/50's and for "16 i run 205/45'sWhat size wheels do you have?
DaddyBuiltRacing
Resident Asshole
Honda speedo's are off from the factory for starters. Secondly I have yet to see any change in my speedo reading by switching from a 55 to a 50 or even a 45. I run 205/50/15's. Lastly, bigger tires are known to throw off speedo's, not smaller tires.
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Torreto
Bird, is the word
thats 100% not true at all, it doesnt matter what "size" the tire is its the ratio thats important. just because you don't notice a different doesn't mean its not off. your speedo WILL be off if your tire ratio is different from stock. im also curious where you heard that stock speedos are off from the factory. I would think that a mutli billion dollar company like honda could hire a few engineers that know how to get it right but maybe thats just me.Honda speedo's are off from the factory for starters. Secondly I have yet to see any change in my speedo reading by switching from a 55 to a 50 or even a 45. I run 205/50/15's. Lastly, bigger tires are known to throw off speedo's, not smaller tires.
DaddyBuiltRacing
Resident Asshole
Trust me they are off, maybe its 1mph or maybe its 3mph, either way they are off. Run your car through one of those "Your Speed xx" things.
Here i found this online after a 2 second search:
"not to mention there is a margin of error for stock speedometers, meaning that you could be 1-2 MPH off from the factory (standard procedure for auto manufacturers since so many things make a difference...)"
Here's further proof:
"Regarding speedo and odometer accuracy……………………
I don’t know if this has ever been covered in previous posts. If you already are aware, or don’t give a shit, then disregard. But for those who are unaware, do care, or are new to Hondas and Acuras, then please read on.
When our Civics and Integras were stock, they came with 14 or 15 inch wheels with multiple tire sizes depending on model. I am here to tell you that the speedo and odometer MAY NOT BE ACCURATE with the stock tire sizes…………………between 3-11% depending on the stock tire size that came on the car. The only way to verify is by taking the car to a speedo calibration shop.
As many know, the whole system runs off the electronic vehicle speed sensor in the tranny and is driven by the supplemental ring gear on the edge of the differential and the gear attached to the speed sensor itself. Unless I am mistaken (95% sure that I am not), both those gears have the exact same ratio regardless of which Civic or Integra B or D series manual tranny you have. I cannot vouch for speedo gears in the automatic trannies. With the stock tire sizes, the only real variable is how the speed sensor electronic voltage signal itself is performing. Swapping speed sensors may or may not solve the problem. Chances are though that the vehicle speed sensor is functioning AS DESIGNED.
I bought my 1995 Civic EX coupe new and immediately noticed this flaw. When my gauges were reading 70mph, I was really doing 64mph. That 9% difference was also consistent at other speeds as well. The odometer was registering 1.1 miles per every mile driven. I had this verified by a speedo calibration shop. I had the stock 185/60/14 tire size. I took the car to the dealer and they replaced the speedo cluster, which didn’t solve anything. When I later went to 195/50/15 tires, the accuracy stayed the same. I drove the car like that for a few years and mentally compensated. My mileage accumulated a few extra thousand miles more than it should have.
In 2001, I switched to my current tire size of 205/40/17. With my original D series manual tranny, my speedo accuracy increased to 99-100% depending on my speed. My odometer has been perfect ever since.
In 2006, I swapped in a B series with an ITR tranny with factory LSD. I had the speedo and odometer checked again and it was exactly the same as my D series tranny.
So in summary, assuming that all B and D series manual tranny vehicle speed sensors are operating as designed, the only true fix is to use a tire size that has a total properly inflated external diameter of 23.5 inches to achieve 99-100% accuracy. Here is a rundown of some of the popular 92-00 Civic and 94-01 Integra tire sizes and their external diameters. These numbers were derived from Toyos website. There may be very small deviations in tire size dimensions from one tire manufacturer to the next. Smaller overall diameters mean more revolutions from point A to B, and vice versa for larger overall diameters. If all you do is race, then smaller is the way to go for most. But of you want accuracy for your street car, then follow this chart next time you decide to go with a new wheel and tire size:
Tire size.............Overall diameter......Reading / Actual................Accuracy rate
205/40/16..........22.5 inches...............70mph / 60.9mph.............87% accuracy
175/70/13..........22.7 inches...............70mph / 62.3mph.............89% accuracy
185/60/14..........22.8 inches...............70mph / 63.7mph.............91% accuracy
195/50/15..........22.8 inches...............70mph / 63.7mph.............91% accuracy
205/50/15..........23.1 inches...............70mph / 65.8mph.............94% accuracy
205/45/16..........23.3 inches...............70mph / 66.9mph.............95.5% accuracy
195/55/15..........23.4 inches...............70mph / 67.9mph.............97% accuracy
205/40/17..........23.5 inches...............70mph / 69.3mph.............99% accuracy
225/50/15..........23.9 inches...............70mph / 74.2mph.............94% accuracy
:
Here i found this online after a 2 second search:
"not to mention there is a margin of error for stock speedometers, meaning that you could be 1-2 MPH off from the factory (standard procedure for auto manufacturers since so many things make a difference...)"
Here's further proof:
"Regarding speedo and odometer accuracy……………………
I don’t know if this has ever been covered in previous posts. If you already are aware, or don’t give a shit, then disregard. But for those who are unaware, do care, or are new to Hondas and Acuras, then please read on.
When our Civics and Integras were stock, they came with 14 or 15 inch wheels with multiple tire sizes depending on model. I am here to tell you that the speedo and odometer MAY NOT BE ACCURATE with the stock tire sizes…………………between 3-11% depending on the stock tire size that came on the car. The only way to verify is by taking the car to a speedo calibration shop.
As many know, the whole system runs off the electronic vehicle speed sensor in the tranny and is driven by the supplemental ring gear on the edge of the differential and the gear attached to the speed sensor itself. Unless I am mistaken (95% sure that I am not), both those gears have the exact same ratio regardless of which Civic or Integra B or D series manual tranny you have. I cannot vouch for speedo gears in the automatic trannies. With the stock tire sizes, the only real variable is how the speed sensor electronic voltage signal itself is performing. Swapping speed sensors may or may not solve the problem. Chances are though that the vehicle speed sensor is functioning AS DESIGNED.
I bought my 1995 Civic EX coupe new and immediately noticed this flaw. When my gauges were reading 70mph, I was really doing 64mph. That 9% difference was also consistent at other speeds as well. The odometer was registering 1.1 miles per every mile driven. I had this verified by a speedo calibration shop. I had the stock 185/60/14 tire size. I took the car to the dealer and they replaced the speedo cluster, which didn’t solve anything. When I later went to 195/50/15 tires, the accuracy stayed the same. I drove the car like that for a few years and mentally compensated. My mileage accumulated a few extra thousand miles more than it should have.
In 2001, I switched to my current tire size of 205/40/17. With my original D series manual tranny, my speedo accuracy increased to 99-100% depending on my speed. My odometer has been perfect ever since.
In 2006, I swapped in a B series with an ITR tranny with factory LSD. I had the speedo and odometer checked again and it was exactly the same as my D series tranny.
So in summary, assuming that all B and D series manual tranny vehicle speed sensors are operating as designed, the only true fix is to use a tire size that has a total properly inflated external diameter of 23.5 inches to achieve 99-100% accuracy. Here is a rundown of some of the popular 92-00 Civic and 94-01 Integra tire sizes and their external diameters. These numbers were derived from Toyos website. There may be very small deviations in tire size dimensions from one tire manufacturer to the next. Smaller overall diameters mean more revolutions from point A to B, and vice versa for larger overall diameters. If all you do is race, then smaller is the way to go for most. But of you want accuracy for your street car, then follow this chart next time you decide to go with a new wheel and tire size:
Tire size.............Overall diameter......Reading / Actual................Accuracy rate
205/40/16..........22.5 inches...............70mph / 60.9mph.............87% accuracy
175/70/13..........22.7 inches...............70mph / 62.3mph.............89% accuracy
185/60/14..........22.8 inches...............70mph / 63.7mph.............91% accuracy
195/50/15..........22.8 inches...............70mph / 63.7mph.............91% accuracy
205/50/15..........23.1 inches...............70mph / 65.8mph.............94% accuracy
205/45/16..........23.3 inches...............70mph / 66.9mph.............95.5% accuracy
195/55/15..........23.4 inches...............70mph / 67.9mph.............97% accuracy
205/40/17..........23.5 inches...............70mph / 69.3mph.............99% accuracy
225/50/15..........23.9 inches...............70mph / 74.2mph.............94% accuracy
:
Torreto
Bird, is the word
you just said that they are off from the factory and now your example is of a 15 year old car? of course the speedo can get off after 15 years there are tons of variables that could cause that. show me a documented study where a brand new honda speedo is off. you are talking about 2 very different things here. and fyi just because its on the internet doesn't always mean its true
DaddyBuiltRacing
Resident Asshole
I can't really take a poster that goes by username of Toretto seriously lol. With that said click >> http://www.caranddriver.com/features/02q2/speedometer_scandal!-feature
but what does car and driver know?
Incase yoru too lazy to click the link, ill point out some of the better areas:
"manufacturers are afforded the latitude to aim for within plus-or-minus two percent of absolute accuracy or to introduce bias to read high on a sliding scale of from minus-one to plus-three percent at low speeds to zero to plus-four percent above 55 mph. And those percentages are not of actual speed but rather a percentage of the total speed range indicated on the dial. So the four-percent allowable range on an 85-mph speedometer is 3.4 mph, and the acceptable range on a 150-mph speedometer is 6.0 mph."
So is it the tire size throwing the speedo off, or is it the fact that its off from the factory thats the culprit? Like I said I see no difference on my speedo from when I had 195/55's vs my 205/50's
but what does car and driver know?
Incase yoru too lazy to click the link, ill point out some of the better areas:
"manufacturers are afforded the latitude to aim for within plus-or-minus two percent of absolute accuracy or to introduce bias to read high on a sliding scale of from minus-one to plus-three percent at low speeds to zero to plus-four percent above 55 mph. And those percentages are not of actual speed but rather a percentage of the total speed range indicated on the dial. So the four-percent allowable range on an 85-mph speedometer is 3.4 mph, and the acceptable range on a 150-mph speedometer is 6.0 mph."
So is it the tire size throwing the speedo off, or is it the fact that its off from the factory thats the culprit? Like I said I see no difference on my speedo from when I had 195/55's vs my 205/50's
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