Spedo Recalibration???
Thread Starter
Racer
Joined: Nov 2006
Posts: 491
Likes: 10
From: Atlanta Ga
Spedo Recalibration???
Changed tire sizes and need to know if I need to recalibrate my speedometer. According to the tire size calculator, going to a 255/35-18 in the front results in a 2.5% too fast reading and switching to a 285/35-19 in the rear is 0.7% too slow.
So what am I to do... Will a Predator handheld allow me to get things reading correctly? Or can I just live with this and always wonder just how fast/slow I'm going?
So what am I to do... Will a Predator handheld allow me to get things reading correctly? Or can I just live with this and always wonder just how fast/slow I'm going?
Team Owner
Joined: Sep 2001
Posts: 23,283
Likes: 906
From: Lake Elsinore, CA
Predator will allow you to adjust for tire size changes, among other things. The more capable packages such as EFILive and HPTuners wil also.
Here's the Predator parameter list.
Here's the Predator parameter list.
- Timing Table 1000-1800rpm (+/- 20%)
- Timing Table 2000-4000rpm (+/- 20%)
- Timing Table 4000-7000rpm (+/- 20%)
- Fuel Table 2000-4000rpm (+/- 20%)
- Fuel Table 4000-7000rpm (+/- 20%)
- Idle (+ 500rpm / -300rpm)
- Speed Limiters (Trucks Only)
- Rev Limiters
- RPM Shift Points
- MPH Up and Downshifts
- Shift Timing
- Shift Pressure
- Cooling Fan ON and OFF temperatures
- Re-Calibrate Speedometer for Gear and Tire Size Changes
- Torque Management abuse mode time limit ON/OFF
- % torque reduction vs. RPM ON/OFF
- Upshift torque reduction (all gears) ON/OFF
- Adjust for different injector size
- Disable P0420 and P0430 codes
- Adjust COT enable temperature
- Misfire Low rev
- Misfire Low cyl
- Misfire idle cyl
- Enable/disable MPH, set high to disable
- Disable P-codes: 0400,0401,0402, 0405, 1404 and 1409
- Disable P-codes: 0410, 0412 and 0418
- Disable P-codes: 0137, 0138, 0140, 0141, 0157, 0158, 0160 and 0161
- All standard DiabloSport Predator features
Burning Brakes
Joined: Jul 2006
Posts: 968
Likes: 12
From: Regina Sask
A 255/35/18 tire height is between 25-25.2" tall depending on the brand. I would use a 265/35/18 front tire instead. A 285/35/19 rear tire is very close to stock dia. or the same dia.,depending on the brand. The front to rear tire dia relationship can't be programmed even with Hp Tuners.
What brand of tires are you looking at?
Russ Kemp
What brand of tires are you looking at?
Russ Kemp
Thread Starter
Racer
Joined: Nov 2006
Posts: 491
Likes: 10
From: Atlanta Ga
i got the BFG Kdws and according to the calculator the following is how they compare:
FRONT
Stock tire new tire
245/45-17 255/35-18
sidewall 4.3 in 3.5 in
radius 12.8 in 12.5 in
diameter 25.7 in 25.0 in
circumverence 80.7 in 78.6 in
rev/mile 785.0 806.0
REAR
275/40-18 285/35-19
sidewall 4.3 in 3.9 in
radius 13.3 in 13.4 in
diameter 26.7 in 26.9 in
circumference 83.8 in 84.4 in
rev/mile 756.0 751.0
FRONT
Stock tire new tire
245/45-17 255/35-18
sidewall 4.3 in 3.5 in
radius 12.8 in 12.5 in
diameter 25.7 in 25.0 in
circumverence 80.7 in 78.6 in
rev/mile 785.0 806.0
REAR
275/40-18 285/35-19
sidewall 4.3 in 3.9 in
radius 13.3 in 13.4 in
diameter 26.7 in 26.9 in
circumference 83.8 in 84.4 in
rev/mile 756.0 751.0
