OD adjustments
- Thread starter NeedMoreCowbell
- Start date
1engineer
Moderator
I'm not proving anything nor did I claim to. I do know that OEM's build to the spec outlined by SAE as I cited in a previous post.That is fact. Oh, I was being facetious with the "your honor" comment. I don't want to get into a disagreement with anyone either. Also proving your groundspeed is not easy. Speeding tickets get overturned every day. As I said before - GPS will get you close and so will your speedometer with a cheat sheet for different size tires. The most accurate way is to trip the lights in a timed mile run.
offroadingatc
New member
Fair enough, sorry I'm busting your b@lls on this, I'm normally a big fan of your posts.
Its just when you make statements like 'if this were the case then x' it seems a lot like you are using x to prove your point.
I guess I cant explain it, I believe what you are saying about SAE standards is true based on the accuracy of your other posts, however I have been in a brand new car that I am 99.99% sure was about 5% off, so not sure what to do with that.
Victor_inox
New member
re: GPS accuracy, it depends on what type of GPS you are using and where. They can be incredibly accurate and a lot of them account for altitude changes and turns etc. Regardless if you are using it to verify your speed and do so in a relatively straight line they calculate speed very accurately for the most part. If you think you cannot judge speed with a GPS i suggest never flying again.[/QUOTE]
Garmin accuracy is 0.1mph
Velocity measured by a GPS is inherently 3 dimension, but consumer GPS receivers only report 2D (horizontal) speed on their readout. Garmin's specifications quote 0.1mph accuracy but due to signal degredation problems noted above, perhaps 0.5mph accuracy in typical automobile applications would be what you can count on.
GPS accuracy is what you can count on if your gps receiving 4satelites signals or more.turns or hills not really affect reading that much.
Garmin accuracy is 0.1mph
Velocity measured by a GPS is inherently 3 dimension, but consumer GPS receivers only report 2D (horizontal) speed on their readout. Garmin's specifications quote 0.1mph accuracy but due to signal degredation problems noted above, perhaps 0.5mph accuracy in typical automobile applications would be what you can count on.
GPS accuracy is what you can count on if your gps receiving 4satelites signals or more.turns or hills not really affect reading that much.
limamike
New member
I think for once I was able to decipher what Victor_inox said, and he was correct for the most part. GPS is very accurate because it relies on time variance. Whether you're going in a straight line, sideways, slantways, longways, or backways you'll get the same accuracy once you're "locked" to the satellite without signal interruption. As far as a device you can install in the vehicle without adding additional sensors to get real-time data, you won't find a better instrument than GPS to get an accurate speed rating.
swansong04
New member
my question is can the dealership do it or not ?? got bigger tires on my dodge 1 ton and the dealership recalibrated my speedo in about 30 seconds ...
harper7
Senior Member
No, the dealer can't do it on 4Runners. There is a list of what they can do in the stickies and that's not one of them.
swansong04
New member
damn!! thanks for the clarification .:shrug:
philsey
New member
1-E, what does it say about me if I had to Google Images to find out who this is, and still don't know why it's funny?
1engineer
Moderator
It says you were a little older and more mature than me when this cartoon came out lol. YouTube it and watch the skit if you think juvenile humor is still funny.
philsey
New member
Sorry for the
fftopic: @OP, but 1-E started it.Ah jeez, I'm officially old. That was stoopid.
Funny (to me)? More Cow Bell, ala most early SNL. As well as Monty Python, Andrew Dice Clay, early Steve Martin, Richard Pryor.
Sigh.
BigredTEX
New member
I bought my T4R with dealer installed lift and 285 tires. The first thing I verified, using a Garmin 60CSx GPS was the speedo accuracy. It was spot on. I had a Ford F150 that I had lifted and installed larger tires and the same GPS verified that the speedo was indicating slow by approx. 7%, which is what I expected based on the new tire size. I never recalibrated the speedo and learned to compensate for it. In my younger days I had a BMW which had a +1 wheel/tire upgrade that gave me a slightly larger rolling radius. I created a cheat sheet based on rolling radius, gear ratios and engine RPM that showed true speed at various RPM readings.
That leads me to believe that the speedo in my T4R has been recalibrated to accurately compensate for the larger diameter tires. With all of this discussion I will recheck my speedo accuracy both with the GPS and by the same calculation method I used before.
