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Question with tires

Venomblue22

If you only knew
Mar 7, 2005
1,237
0
Hey im runnin 295,35 18s in the rear, and 275,35 18s in the front, now the fronts are the overall same size as factory, but the rears are a 1/2 in taller. Now the abs light is on, and the traction control is off, Does any body know if the dealerships can adjust the computer to reconize, the bigger tires, and the difference between the 2 different tires so th the abs wks, and i can turn the traction on and off again, also, can you buy a flash tuner and adjust so??
thnx
chris
 

Flatliner

I'm kind of a big deal...
Mar 3, 2004
35,000
0
Ok, I am gonna give my .02, but someone else can chime in to...

1) ABS light should not be effected by tires... my first thought may be to check owners manual on what the light means, and I would guess something about brake fluid level, check it. Are you sure the ABS light is not the traction control(don't get mad... I thought something was wrong with my car when I first got it and my attempt to a smoke show went sour...)

2) What will be effected is your speedometer... if the tire is taller, than I think your speedometer will show your are going slower than you really are.

3) Flash tuner can- a) adjust speedometer b) turn off traction control (I left mine untouched.)

3)
 

Mystic Terminator

TCG Elite Member
Oct 6, 2004
3,150
0
Venomblue22 said:
Hey im runnin 295,35 18s in the rear, and 275,35 18s in the front, now the fronts are the overall same size as factory, but the rears are a 1/2 in taller. Now the abs light is on, and the traction control is off, Does any body know if the dealerships can adjust the computer to reconize, the bigger tires, and the difference between the 2 different tires so th the abs wks, and i can turn the traction on and off again, also, can you buy a flash tuner and adjust so??
thnx
chris


Tire Size Comparison​

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
275/40-17 4.3in 12.8in 25.7in 80.6in 786 0.0%
295/35-18 4.1in 13.1in 26.1in 82.1in 772 1.8%

http://www.miata.net/cgi-bin/tirescgi

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

Speedometer reading with non-stock tire is 1.8% too slow.
When your speedo reads 60 mph, you are actually traveling 61.1 mph

Don't expect the dealer to fix your speedo w/ flash. PM flyn high again, he needed to buy the speedo correction box when dealer changed his gears. He can tell you which one he used and if it will work w/ tire changes also.

Predator Features:
Dual timing adjustment points (2000-4000 RPM / 4000-7000 RPM)
Timing table (+10% / -40%)
Dual fuel adjustment points (2000-4000 RPM / 4000-7000 RPM)
Fuel table (+40% / -15%)
Idle (+/- 20%)
On/Off switch for Traction Control
Rev Limiter
Re-Calibrate Speedometer for Gear and Tire Size Changes
Cooling Fan ON/OFF Temperatures
Rear Oxygen sensor disable (use for off-road vehicles only)
Disable EGR (use for off-road vehicles only)
Adjust at what rpm the shift light comes on
 

Flyn

Go ahead. I'll catch up.
Moderator
TCG Premium
Mar 1, 2004
68,052
27,984
Selling homes on the Gulf Coast of Florida
Check the code first. I have 285/40/17 and 275/40/17 with no lights. I used the SpeedCal recalibrator from Dallas Mustang to adjust for my 4.10 gears but I don't know if it will adjust for size differences between front and rear tires. I doubt your slight size difference is enough to throw the code. :dunno:
 

Venomblue22

If you only knew
Mar 7, 2005
1,237
0
first off, i have a scanner, so i can get the code no prob, second of all when you have two different size tires, they are spinning at diff speeds, so your abs gets way out of wack, reason i know this is, notice when your car is on the dino, your ft tires are not spinning, and your rears are, your abs light will come on afeter a while, its the same concept here it just took 50 miles to realize that the ft and rears are spinnin at 2 dif rates, and yes my abs light is on, and my traction control light is on, i als ocan not turn on traction controll cuase of the the tires,i apreciate the help, but do you know if the dealership can adjust it on the comp, i asked the guys at packey today, and they said call monday so ill see, thanx, and any more info would help
 

nytebyte

Not Politically Correct
Mar 2, 2004
13,627
20,958
Different circumference tires can mess up the traction control. I wouldn't think 1.8% of a difference would be enough, but maybe it is.

I have 275/40 in front and 285/40 in back which is a 1.2% difference. The ABS actually does seem more sensitive, but it doesn't register a malfunction.

If you have a Predator, you use it to adjust for tire size.
 

nytebyte

Not Politically Correct
Mar 2, 2004
13,627
20,958
Venomblue22 said:
do you know if the preditor can adjust for 2 different size tires tho?

If you're referring to larger tires in the back and smaller ones in the front, I'm not sure.

Here is the description of the function from the Preditor manual:

Tire revs per mile = Adjust for larger / smaller tire diameter to correct speedometer.
To get revs per mile use overall tire diameter in inches 20168 divided by tire diameter = revs per mile

It doesn't say anything specifically about the ABS. You should contact Diablo and ask them directly.
 
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