It would effectively be lower geared but would stuff up: speedo reading/all fuel calculations/odo reading (pay more RUC?) anything else?
Is it possible to change speed reading?
Anyone clever enough to know work out if I take an inch or two off the wheel diameter what difference that will make to my speedo ? I would like to lower speed on all gears by 10-15km/h.
mainlander05,
Jan 5, 6:47am
And if its outside the recommended sizes,you may also put the wolf at risk.be very carefully here.
lookoutas,
Jan 5, 6:49am
Don't ever do it to a white one.
kevymtnz,
Jan 5, 6:50am
going from eg 15in 205/70 to 205/60 would be 4kph what your trying is lower profile and down one size
thewomble1,
Jan 5, 6:52am
To get correct speed use a GPS unit or your mobile phone. Do 50kmh using GPS and the see what the car speedo reads. Again at 100kmh on GPS and check car speedo.
timbo69,
Jan 5, 6:53am
Current size is 225/65/17
alfred011,
Jan 5, 6:54am
You would need to know gear ratios ,gearbox and diff then you would need to know tyre circumference,the speedo would read faster than the vehicle is going as it would gear it down so would use more fuel as it distance travelled would be less per tyre revolution.
My ute does 130km/h at 2000rpm in 6th gear - I basically dont use 6th as I tow a lot. I reckon I will improve fuel economy as I will be able to get away much easier and then cruze in 6th at 90-100km/h rather than 5th
timbo69,
Jan 5, 7:06am
Will do this after. just trying to understand the effects of what im considering.
lookoutas,
Jan 5, 7:39am
The first effect you're gunna get, is that no-one can give you any advise without knowing what the hell drives your speedo. To achieve this, it will help to know what the hell make of ute it is. Otherwise we're all wasting time trying to work out if crystal balls actually work!
The main effect that you need to address is running up RUC's that you aren't doing, hence you need to recalibrate the speedo, but no-one can make a suggestion. Is it electric or cable driven?
The speed difference can be sorted with GPS, and you shouldn't know or admit that 130KPH = 2000RPM.
Are you clitty with a different account?
intrade,
Jan 5, 7:43am
you need larger wheel for less ruc . smaller wheels need to rotate more to travel same distance
curlcrown,
Jan 5, 7:45am
Gearbox and diff ratio wouldn't need to be known. The only thing changing is wheel diameter. You only need to know the current size and the new size to be able to work out the percentage difference in speed at any speedometer indicated speed and difference in distance travelled at indicated odometer reading since the change is made.
The speed difference can be sorted with GPS, and you shouldn't know or admit that 130KPH = 2000RPM.
Why? its just a calculation of doing just about 95km/h at 1500RPM - under my usable part of my torque curve.
timbo69,
Jan 5, 8:01am
Some people like to complicate things.
lookoutas,
Jan 5, 8:04am
Second para, first post: Is it possible to change speed reading?
That's what OP wants to know. Has anyone here sorted out what the ute is? It could be a 1932 Model A Lada - with electronics.
timbo69,
Jan 5, 8:04am
That is a brilliant calculator.
timbo69,
Jan 5, 8:09am
Sorry, its a 2014 Colorado - im sure its highly unlikely it can be adjusted. There would be some interesting things you could do if it was possible
timbo69,
Jan 5, 8:18am
Looks like a 225/55/16 would give me about 11%.
lookoutas,
Jan 5, 8:31am
OK - so now someone who knows can tell you if it can be recalibrated.
If it was a simple old cable/gear drive, they usually have about 4 different gears that can be interchanged to adjust the reading. But I wouldn't have a bloody clue how the electronic ones work. There could be a gear drive running a sender unit, or it might run on pulses.
If you hadda come back and said it was an XY Coon box, I could've told you what to do. And that's change the gear drive in the box to a gear with an extra tooth. If it's got a gear driving a sender unit at the box, the same will apply.
supernova2,
Jan 5, 8:36am
As far as RUC goes can you fit a hubo instead of using the odometer?
lookoutas,
Jan 5, 8:40am
Have heard that you can get it calibrated and certified as being incorrect, then pay accordingly to the recorded calibration.
tweake,
Jan 5, 9:36am
don't forget any tyre over 5% difference in circumference from what it originally came out with requires certification.
beno,
Jan 5, 11:19am
the brake calipers will be too big for the smaller wheels so you might have to change them too. also, the abs might throw up a trouble code as the transmission will be expecting the wheels to be turning at a certain speed for the RPM so the ABS ecu might think the wheels are slipping. The handling characteristics will change too if the wheel offset is fiddled with
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