Tachometer Reading at Cruising Speed

[CustomGolf]

For mine at 80km/h at 2000rpm, 90km/h at 2100rpm, 100km/h at 2200rpm. Driving AT.

You sure bro, your meter dial is 200rpm per mark so at 100kmh it should be 2 marks above 2k so it should be 2.4K rpm. Unless you're saying your meter dial is just 1 mark above 2k when you're at 100kmh.

[clarence]

Perhaps he upgraded his rims and tyres to a wrong size and hence his speedometer is giving an incurrate reading - slower reading than actual speed.

[Jazz]

Nope, I don't think there will be a difference in READING the speed on you meter dial when you up your tyre size, it's still based on your standard tyre size unless your car is so futuristic that speed is not measured using parameters preset in the ECU or based on your wheel rotation speed but an external source or you've re-calibrated your meter after changing wheels.

I'm using 205/55/16 and my rpm is still at 2400 when I'm travelling at 100kmh.

Google and read about the tire profile size do affect speedometer reading. The ECU unable to re-calibrate to the new rim size and tire profile for your info. Bear in mind that our speedometer is analog, not accurate to gauge or judge the actual speed or RPM.

Lastly your speedometer reading with 205/55/16 is 1.67% slower compared to your stock size

[CustomGolf]

Google and read about the tire profile size do affect speedometer reading. The ECU unable to re-calibrate to the new rim size and tire profile for your info. Bear in mind that our speedometer is analog, not accurate to gauge or judge the actual speed or RPM.

Lastly your speedometer reading with 205/55/16 is 1.67% slower compared to your stock size

That is precisely what I'm trying to explain, it shows 100kmh and tacho is 2.4k rpm, I'm going above 100kmh but it's not registered. It just don't show up in your meter dial so it should show the same no matter what tyres you're on. Those 2 figures are constant no matter what rims and tyres you're on unless you go calibrate. So where did the variance come from if every one is using the same gear box ratio and same calculation of tyre circumference.

[clarence]

Use the link below to gauge if your tyre and rim upgrade is of the correct size.

If the size is incorrect, you are likely to get incorrect speedometer reading.

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

[FamilyManz]

That is precisely what I'm trying to explain, it shows 100kmh and tacho is 2.4k rpm, I'm going above 100kmh but it's not registered. It just don't show up in your meter dial so it should show the same no matter what tyres you're on. Those 2 figures are constant no matter what rims and tyres you're on unless you go calibrate. So where did the variance come from if every one is using the same gear box ratio and same calculation of tyre circumference.

  thats is the reason why I always advise my associates when they change their sizes over the 2% mark, against stock.....

the actual speed will not be reflected on the meter.

[alangohek]

4AT??? Impossible..... even if u let go of the accelerator....

I manage to get 2000rpm at 100kmh cruising on a flat load without passenger and empty boot. Petrol I am using is either Caltex RON 98, Shell RON 98 or Vpower. Stock rim and tyre.

May be because my car still less than 3 months old.

Haha

Rgds

[CustomGolf]

Use the link below to gauge if your tyre and rim upgrade is of the correct size.

If the size is incorrect, you are likely to get incorrect speedometer reading.

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

Brother follow the link http://forum.thelatioclub.org/index.php?topic=364.0, we're not talking about incorrect speedo reading in the thread here but the relation between speedo reading and RPM reading.

[clarence]

An incorrect speedo reading will affect your rpm reading too.

For example, if because of your incorrect upgraded tyre size, your speedo reading is faster than the actual speed by 3%.

Hence, when your speedo shows 100km/h, you are actually travelling at only 97km/h.

[Jazz]

An incorrect speedo reading will affect your rpm reading too.

For example, if because of your incorrect upgraded tyre size, your speedo reading is faster than the actual speed by 3%.

Hence, when your speedo shows 100km/h, you are actually travelling at only 97km/h.

Spot on. 

[idiotboi89]

I manage to get 2000rpm at 100kmh cruising on a flat load without passenger and empty boot. Petrol I am using is either Caltex RON 98, Shell RON 98 or Vpower. Stock rim and tyre.

May be because my car still less than 3 months old.

Haha

Rgds

wah lao.. den my 4at sounds to love to rev abit more den 

[baobao]

yo.. does it mean our 4AT drink more petrol than the CVT version? is the diff in FC big?