Gear ratios and RPM at cruising speeds? - Subaru Enthusiasts Car Club of the Sierras

Dean · 2011-04-03, 06:32 PM

From our earlier conversation on this, I made some observations on the way home from Fernley and would be interested to see what other people in other cars get in the real world vs. what the specs say they are.

Everything is rounded to as close as I could get/estimate and hold for some time in a straight line on cruise.

Code:

Car: '04 STI
Wheels: 17x8 RPF1s
Tires: 225/45/17 RE070s
Gear RPM  Speedo GPS Speed
6th  2750  70       66
6th  2900  75       70
6th  3100  80       75

Speedometer error is pretty interesting considering these are the OEM tires on only slightly wider wheels.

sperry · 2011-04-03, 11:07 PM

The speedo is well known to read high. It's great for running massive snows on the car and having a more accurate speedo rather than less accurate.

100_Percent_Juice · 2011-04-04, 06:57 AM

I will have to do this again. I remember I tried this when I first got my Garmin and I think it was pretty accurate.

cody · 2011-04-04, 07:25 PM

With my stock size snows, my TomTom says I'm going about 58 when the speedo says 60.

szucchet · 2011-04-04, 07:56 PM

my 04 sti is about the same as deans except my is on 255/40/17

Double Phister · 2011-04-05, 08:39 AM

I know the speedo is off. I wonder how accurate the odo is. I'll bet the error is not the same.

A1337STI · 2011-04-05, 12:14 PM

My sti speedo to GPS (on stock sized tires) was reading the same way.

WRXlerate · 2011-04-06, 10:30 AM

Now I see why I have not had a speeding ticket in a while. I think I'm doing the normal 10 over on the freeway but am really only doing 5 over.
Good to know.

Dean · 2011-04-06, 11:39 AM

Come on, somebody with a WRX, preferably bugeye 5MT, do the whole RPM/Speedo/GPS thing, please...

cody · 2011-04-06, 11:44 AM

I'll try it on my way home.

k-dogg39 · 2011-04-06, 01:10 PM

I should be on the freeway this weekend, so I can check mine too with the 6-speed.

A1337STI · 2011-04-06, 03:40 PM

I'll do some testing with my 93 RS once its running. (98 transmission)

oh last night speedo 65, GPS 65 Tire size? 215/55/17 5.4% over sized.

szucchet · 2011-04-08, 11:59 AM

Quote:

Originally Posted by WRXlerate

I think I'm doing the normal 10 over on the freeway but am really only doing 5 over.
Good to know.

NO... bad to know, i wish i did know because i compensate for it

2011-04-03, 06:32 PM	#1
Dean Señor Cheap Bastarde Real Name: Dean Join Date: May 2003 Location: $99 Tire Store Posts: 9,294 Car: $.04 STI Class: Fast,Cheap & Reliable=STI Deal, did somebody say Deal? Oh, Dean, yeah that's me.	Gear ratios and RPM at cruising speeds? From our earlier conversation on this, I made some observations on the way home from Fernley and would be interested to see what other people in other cars get in the real world vs. what the specs say they are. Everything is rounded to as close as I could get/estimate and hold for some time in a straight line on cruise. Code: Car: '04 STI Wheels: 17x8 RPF1s Tires: 225/45/17 RE070s Gear RPM Speedo GPS Speed 6th 2750 70 66 6th 2900 75 70 6th 3100 80 75 Speedometer error is pretty interesting considering these are the OEM tires on only slightly wider wheels. __________________ I am a Commodore PET --- Now get off my lawn you kids... Last edited by Dean; 2011-04-03 at 06:34 PM.

2011-04-03, 11:07 PM	#2
sperry The Doink Real Name: Scott Join Date: Nov 2002 Location: Portland, OR Posts: 20,335 Car: '09 OBXT, '02 WRX, '96 Miata Class: PDX/TT-6 The way out is through	The speedo is well known to read high. It's great for running massive snows on the car and having a more accurate speedo rather than less accurate. __________________ Is you is, or is you ain't, my con-stit-u-ints?

2011-04-04, 06:57 AM	#3
100_Percent_Juice (40 percent vodka) Real Name: Joel Join Date: Oct 2006 Location: Reno, NV Posts: 4,446 Car: 2004WRX Class: Baby-Hauler/GroceryGetter	I will have to do this again. I remember I tried this when I first got my Garmin and I think it was pretty accurate. __________________ "A power nap is when you sleep on someone who is weaker than you." - Dimitri Martin

2011-04-04, 07:25 PM	#4
cody Candy Mountain Real Name: Cody Join Date: May 2005 Location: Californication Posts: 7,751 Car: 03 Pussy Wagon, now with more pink! Class: TESP OMG Internet!	With my stock size snows, my TomTom says I'm going about 58 when the speedo says 60. __________________ Slow and low, that is the tempo.

2011-04-04, 07:56 PM	#5
szucchet EJ22 Real Name: Silvio Join Date: Jul 2008 Location: sacramento, ca Posts: 271 Car: 2004 Subaru STI Class: 04 TSM smooth is fast	my 04 sti is about the same as deans except my is on 255/40/17 __________________ funny how day by day nothing changes, but when i look back everything is different

2011-04-05, 08:39 AM	#6
Double Phister EJ22 Join Date: Mar 2005 Location: Elk Grove, CA Posts: 450 Car: 2005 WRX STi "I'm sideways and in control... I look good."	I know the speedo is off. I wonder how accurate the odo is. I'll bet the error is not the same. __________________ Dan - '05 Black WRX STi. My Mods

2011-04-05, 12:14 PM	#7
A1337STI EJ205 Join Date: Jan 2006 Location: Reno, NV Posts: 1,840 Car: Impreza and an Impreza Class: AS / CRS PerfStock "pedal on the right"	My sti speedo to GPS (on stock sized tires) was reading the same way. __________________ Fighting uphill battles, one bullet at a time!

2011-04-06, 10:30 AM	#8
WRXlerate EJ22 Real Name: John B. Join Date: May 2005 Location: Behind a brick wall. Posts: 471 Car: 02 Soccermom Wagon Class: "sleeper" Destroying V8 Egos 4 cylinders at a time	Now I see why I have not had a speeding ticket in a while. I think I'm doing the normal 10 over on the freeway but am really only doing 5 over. Good to know. __________________ Stuff sold by the gram is always more exciting than stuff sold by the pound. JC

2011-04-06, 11:39 AM	#9
Dean Señor Cheap Bastarde Real Name: Dean Join Date: May 2003 Location: $99 Tire Store Posts: 9,294 Car: $.04 STI Class: Fast,Cheap & Reliable=STI Deal, did somebody say Deal? Oh, Dean, yeah that's me.	Come on, somebody with a WRX, preferably bugeye 5MT, do the whole RPM/Speedo/GPS thing, please... __________________ I am a Commodore PET --- Now get off my lawn you kids...

2011-04-06, 11:44 AM	#10
cody Candy Mountain Real Name: Cody Join Date: May 2005 Location: Californication Posts: 7,751 Car: 03 Pussy Wagon, now with more pink! Class: TESP OMG Internet!	I'll try it on my way home. __________________ Slow and low, that is the tempo.

2011-04-06, 01:10 PM	#11
k-dogg39 Little Slugger Real Name: Kevin Join Date: Jan 2007 Location: North Lake Tahoe, NV Posts: 777 Car: 05 WRB STI Wagon/00 BRP GC Sedan Class: 39 TSM I'm not crazy, I'm just passionate!	I should be on the freeway this weekend, so I can check mine too with the 6-speed.

2011-04-06, 03:40 PM	#12
A1337STI EJ205 Join Date: Jan 2006 Location: Reno, NV Posts: 1,840 Car: Impreza and an Impreza Class: AS / CRS PerfStock "pedal on the right"	I'll do some testing with my 93 RS once its running. (98 transmission) oh last night speedo 65, GPS 65 Tire size? 215/55/17 5.4% over sized. __________________ Fighting uphill battles, one bullet at a time!