How fast are you going...

[lousailor]

I had 205/60/15s front and 235/65/15s in the rear. It definately gave the car an agressive look (lower in the front, big tires in the back, very Old School). Unfortunatley it meant I was always beating up the front spoiler, the speed was off, and I'm sure it caused more stress on the drivetrain to spin up the rears. I just went back to stock all around, and I can really feel and see the difference.

[shocker1322]

The best way to measure the accuracy of the speedometer is to go a known distance ( 3-5 miles is ideal) and check to see how far the odometer changed. Just a simple math calculation to see how far your speedometer is off (it at all) then. We always do this when different tires are put on the cars. Changing tires is just as good as swapping gears, but messes with your speedometer.

[TCMdocs944]

HHmmmm

CJf - I think I like the 225r 215 front idea.

Nobody with pics?

Right now mine has 215's all around and really needs tires bad.

Ok, Ok......PICS! If anyone has them don't be shy.

225's all around?

225r 215f ?

[Manute]

For those of you who don´t have the manual,this would help a bit...gear ratios

Pre 85



Post 85

[Zlatko]

First - up to 50
Second - 80
Third - 120
Fourth - 160
Fifth - 210

K..im gonna try shifting at these RPMs when i get the car on the road..

[rob83944]

I found this speed/gear ratio Excel spread sheet on the www.924.org site under downloads. It gives speed based on tire size and rpm. For the 944, look in the 944 column.

If you have Excel, you can enter your tire size, 225, 215, etc, tire ration 60, 50, ect and then enter rpm and it will calculate the speed in gears.

http://www.924.org/Downloads/PorscheTrans1.xls

The closest speed to OEM tires for the 83 944 (215/60 X 15) was 225/50 x 15 at 3000 RPM in 5th. 80 MPH (215/6- x 15) vs 81 MPH (225/60 x 15).

I am losing about 5 MPH at 3000 rpm using the 225/50 x 15 tires in 5th gear.

[Don 944 LA]

Mt speedo actually doesn't work.
I use a GPS thats VERY accurate.

If you know someone that has a GPS that youy can borrow, that would be the way to go top check the accuracy of the speedo.

I have found that ALL speedos are inaccurate.
Below 35 MPH they are off 5% (fast) , above 40 off 1-2% (slow).

Just my opinion

[Zlatko]

Something's not right...

I have a 1983 944.

On my way home tonight..i was doing 120 MPH at approximately 4300 RPM....now when i look at the chart...those 2 figures are NOWHERE close to each other...

I dont know which one is off..my tach or my speedo..

But i hit 120 before..i know what it feels like..and i was definetly cruising at that speed..

Also...i found that if i completely floor it...the car actually goes SLOWER than let's say...3/4 throttle

[justin]

Originally posted by singpilot
Borrow a friends GPS unit. Everyone has one. Do the comparison yourself. Will need to be on the dashboard to get a sky view.

Everyone but me and people I know....LOL

[Capndar]

Do you have the same final drive ratio as the charts?

[bryanthompson]

Originally posted by Zlatko
Something's not right...

I have a 1983 944.

On my way home tonight..i was doing 120 MPH at approximately 4300 RPM....now when i look at the chart...those 2 figures are NOWHERE close to each other...

I dont know which one is off..my tach or my speedo..

But i hit 120 before..i know what it feels like..and i was definetly cruising at that speed..

Also...i found that if i completely floor it...the car actually goes SLOWER than let's say...3/4 throttle

Zlat, in my 83 the speedo says 100mph at 4k. I'm off by +5mph at 60. What's your rpm when your speedo's at 100?

[Zlatko]

Manute...your charts confuse the hell out of me..

Are you sure this isnt for the 944 Turbo?

Cause my car by comparion is NOTHING like those charts :|

[Manute]

No,they are´nt from the turbo,i downloaded the n/a manuals just for curiosity;are you sure you didn´t made wrong the conversion of kmh/mph?
As seen there,5th gear 6000 rpm means about 220 kmh, the turbo chart says about 250 kmh at the same rpm.

Maybe euro specs are different,but I don´t think so,referring to the gearbox.Gear ratios are fixed,if car is stock (and tires),speed and rpm must be like in the chart...I´m confused too, ´cause it seems like each one has it´s own ratios here...

[Manute]

Originally posted by Zlatko
First - up to 50
Second - 80
Third - 120
Fourth - 160
Fifth - 210

K..im gonna try shifting at these RPMs when i get the car on the road..

Damn i´m just thinking you confused kmh with mph...these are euro charts! your shifting points in mph would be like this:

First - up to 31
Second - 50
Third - 75
Fourth - 100
Fifth - 130

[repoman]

those charts are from owner's manuals so if there is one in your glovebox, look in index