to all the pro, im a little dumb to comprehend all the super word here lol
so would like to ask..
if ori 13" rim can cover 1m per revolution
so a 15" can cover 1.15m per revolution correct?
that means in actual speed, taking 13" as relative figure
100km/h in 13" = 115km/h in 15" but the meter in 15" still showing 100km/h?
please dont bother about the actual figure, juz a sample

my iswara clocked 110kmh at 3.5k rpm

Tonight not free leh....

My car is 110km/h at 2700 rpm.

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Added on August 1, 2008, 6:51 pmAgain, you are thinking about tyre. Speedometer takes the reading from gearbox, not the tyre. To the speedometer, your tyre only turned 1 revolution. It does not car how far you traveled because the calculation has been set by the manufacture to take the revolution of the tyre and calculate based on a preset of formula done by the manufacturer.

That is why when you change to a tyre that does not match your OEM overall diameter (OD), then your speedometer will no longer as accurate. The speedo will still show you the same speed (number of tyre revolutions still same) but you are traveling faster (if you have bigger tyres).

Understand now?

Edited: Going to use your formula..

if ori 13" rim can cover 1m per revolution
so a 15" can cover 1.15m per revolution correct?
-Correct but it is still 1 revolution of the tyre.

that means in actual speed, taking 13" as relative figure
100km/h in 13" = 115km/h in 15" but the meter in 15" still showing 100km/h?
please dont bother about the actual figure, juz a sample
-Correct because if it took 100 revolutions to reach 100km/h in 13 inch, it also takes 100 revolutions to reach 115km/h in 15".
-Your speedo is based on the 100 revolutions and not the distance.

-Understand now? (Ignore figures.. ahahha)

This post has been edited by sleepwalker: Aug 1 2008, 06:56 PM

honda civic eg 1.6L Auto - 3100rpm @ 110km/h

Too keep it simple....yes your assumption is correct.
It is advisable for those that changes their rim size to re-calibrate their speedo. But obviously who wants to go through that hassle.
Also, lack of equipment to do that too.

so where can i 're-calibrate' my speedo?
i changed to 4G92 MIVEC halfcut from Mirage Cyborg (or is it ASTI?)
anybody know what is the ori rim size?

The difference would be so small that it would not matter. Furthermore, most Proton cars are based on the pre 96 Mitsu's and most likely use the similar tyre sizes. Even if there is a difference, it would be in the region of 1 to 2 percent. Not worth the effort.

try adjust the caburator setting such as AFR... recently after adjusted my full tank RM50 can go 350km++
but my kancil is 660cc manual tranny installed with 14" rim, so at 110km/h is 4.2krpm
since bought new car, my kancil never cruising highway anymore lo
persona 110km/h @ 3.2krpm

This post has been edited by ! Love Money: Aug 1 2008, 07:47 PM

your main interest is in the fuel consumption rite?
the lower the RPM, the better the fuel consumption. only true when you're cruising and maintaining the same pressure on the accelerator.

but lets say (for Auto) you're driving at the lowest RPM with the lightest pressure on the accelerator, the gearbox might not change to the final gear, thus you're wasting petrol because slower when compare to final gear speed at the same RPM.

and for Manual, because of the assumption that lower RPM gives better FC, you might change gear too early and thus need to have higher pressure on the accelerator to build more momentum, which lead to wasting petrol.


basically to get lowest FC, is to get the optimum pressure on the accelerator vs the RPM speed.
but this is my theory lar.
correct me if i'm wrong.

I also don't think lower rpm=lower FC. Using proper gear and throttle control is. Last time my car got vacumm meter, I can easily see how much I depressed the gas pedal. if I'm doing 50km/h, I use 4th gear.

i usually onli go to max 2.5k rpm.

my car oso 2700 rpm @11km/h

erm...my civic ej6 b16a manual 4k rpm at 110kmh..but last time auto reach 3k at 110kmh....so manual sux?????

camry 2.4L (08) -after settle down to final gear: 2100 rpm @ 110 km/h

anyone driving accord / mazda 6 care to share similar info?

AT and MT uses different gear ratios. Ratios is all about compromise, you may get lower rpm in the top end but at the expense of the low end.

Civic FD 1.8, 110 km/h @ 2.1k rpm

Wow, what a number.

thats fast dude.. 1st gear eh?

ur fc are soo safe?wat did u mod btw?
my rpm for kelisa is 3k plus when reach 110km/h

proton wira...3.7k rpm...