RS2 speed in different gears

[Jamo]

not exactly a tough calc though is it Jamo

no but you will be surprised how much difference the speeds come out at especially with rounding if you try different variables, which is why I verified against someone who had verified his speed to the various calculators

[Error404]

not exactly a tough calc though is it Jamo

[Jamo]

doing this the hard way!

There's online calculators that do this all for you from the tyre size and will calculate the speed of all gears to rpm! http://www.car-videos.net/tools/speedrpm.asp

I have already pre calculated mine and checked them with pnanassy

A word of warning though I've found a few calculators that give different settings.

I based mine on Alex Hoys output and found one that worked well but I haven't got the link anymore, all I can remember is it's a green webpage

[driftin jo]

I use a Road Angel which is just for speed really too, but my Garmin satnav is also the same as the Road Angel?

I also found this as I was looking to put wider tyres on the rear, to make sure the rolling radis was the near the same for the diffs sake.
http://alloywheels.com/tyrecalc.asp

I use this one , very useful aren't they .

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

[driftin jo]

I use a Road Angel which is just for speed really too, but my Garmin satnav is also the same as the Road Angel?

your speedo was probably only reading 0.8 % out then as the 225/40/18 makes it read 0.8 % slower than stock size.

[Big Lee M]

I use a Road Angel which is just for speed really too, but my Garmin satnav is also the same as the Road Angel?

I also found this as I was looking to put wider tyres on the rear, to make sure the rolling radis was the near the same for the diffs sake.

http://alloywheels.com/tyrecalc.asp

[driftin jo]

I run 225-40-18's on mine and the speedo reads bang on to the GPS speed?

They may well vary on how much they read out , running 225/40/18 will definitely bring you closer to correct speed than stock tires . Mine still exaggerates by about 2 mph .
What gps do you use for speed ?
I use a road pilot and it is solely for speed purposes ,it uses more satellites than my sat nav and has a guaranteed accuracy of + / - 0.5 mph .

[Big Lee M]

I run 225-40-18's on mine and the speedo reads bang on to the GPS speed?

[driftin jo]

A wile ago I had a friend of a friend going on about how fast his souped up astra was , I went out in it as he insisted , when the speedo got to 60 I though to myself this is never 60 mph .
I went and got my gps speed device from my S2 , turns out it was only doing 53 mph when speedo was at 60 . It wouldn't even do 60 in second , so he went form thinking his car did 0 -60 in 6 seconds to finding out he actually needed 3rd gear for that and his real 0-60 was nearly 8 seconds .
He was so pissed off .
Then I took him for a quick spin in the S2 to show him what fast is . :mischeif:
. I'm not sure but I think he went home and hung himself .

[A80Avant]

yes, that is what i use, 245/35/18 so its very close to 629. i think a couple of tyre calculators bring it up at around 628+ so no big difference.

Good info Error, all vems users with a speed sensor can now use this calculation!

[driftin jo]

so a 235/40 18 would read just about spot on then I guess

yes , speedo would be good with this size . probably read about 1 mph over , Close enough

[Error404]

so a 235/40 18 would read just about spot on then I guess

[driftin jo]

AFAIK he's running 245/35 18s

Even worse then as 245/35/18 is (628.7 mm)

just a little

[Error404]

AFAIK he's running 245/35 18s

[driftin jo]

judging by the diameter of tire you have given (629mm) I take it you are using a 215/40/18 ?

The reason I say is this is slightly less than the stock tire diameter of (632mm) for a 205/55/16.

The thing is that with the stock tire the speedo reads too fast by about 5mph / 8 kph .
The tire you are using will increase this error even more .
I have a satellite speed device that is guaranteed to .5 mph and my S2 speedo over reads by 2.5 mph and I run 225/40/18 (637.2mm) diameter.


So unfortunately this means your not going as fast as you think .