Need Technical Help

[edwardwitt]

I realize this is a very mild modification, but would appreciate some technical help. I'd like to switch out my '09 6 i Sport 16" steel wheels for the OE 17" alloy wheel with the OE tire size that comes standard on some higher trim 2009 6 models. The 17" alloy wheel was not an option on the i Sport model, and I'm not sure if that is just due to trim level packages, or if there are other technical reasons. Would doing so affect the speedometer/odometer, fuel program, ABS or DCS, or would the 17" OE wheels & tires be completely compatible? Thanks for your help.

[Mz6GreyGhost]

As long as you get the TPMS systems to calibrate (which should be VERY easy to do), swapping to the OEM 17" wheels/tires should be no problem.

[edwardwitt]

QUOTE (Mz6GreyGhost @ Oct 25 2009, 03:21 PM)

As long as you get the TPMS systems to calibrate (which should be VERY easy to do), swapping to the OEM 17" wheels/tires should be no problem.[/b]

Thanks. I did check to make sure that the TPM sensors for both the 16" steelies and the 17" alloys were the same part number. This tells me that the TPM system will be fine. I know that other makes/models must reprogram PCM pinion factor or else the speedo will be off. It seems as though this is not an issue with Mazda. I suppose the overall height of both tires would be nearly identical.

[edwardwitt]

QUOTE (6rookie09 @ Oct 25 2009, 10:45 PM)

Thanks. I did check to make sure that the TPM sensors for both the 16" steelies and the 17" alloys were the same part number. This tells me that the TPM system will be fine. I know that other makes/models must reprogram PCM pinion factor or else the speedo will be off. It seems as though this is not an issue with Mazda. I suppose the overall height of both tires would be nearly identical.[/b]

Does anyone have experience with this? Does the PCM need to know what size tires are on the vehicle? Any Mazda techs on board?

[Brampton6s]

Use this to calculate your new tire size


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

[edwardwitt]

QUOTE (Brampton6s @ Oct 29 2009, 12:00 AM)

Use this to calculate your new tire size


http://www.miata.net/garage/tirecalc.html[/b]

Thank you very much. That is way cool. I'm going to bookmark it for future use. According to the calculator, my speedo would be off (fast) 0.7%, meaning that when showing 60 MPH, actual speed would be 59.6 MPH. Does that mean that for every mile I travel, my odometer will record 1.07 miles, or 700 "extra" miles for every 10,000 miles? Is there any way to let the PCM know that the tire size has been changed to avoid this? thanks

[Trippp]

I wouldn't worry about such a miniscule change in diameter. As tires wear, for people that swap on snow tires, everytime you take a corner and the inside tires revolve less than the outside tires . . . . there are lots of variables in daily driving that can minutely affect an odometer's accuracy. Throw in 6 months of wheel spin in snowy New England and you're probably talking hundreds more miles over the life of a vehicle. Flat tires and donuts... Even over/under inflation can affect a tire's rolling diameter.

Point being, if there was some way to to accurately and scientifically measure mileage in day to day use and compare to a car's odometer, I bet we're all off by hundreds of miles anyway. Many people (including myself on past Hondas) swap out to a comparable OEM upgrade all the time. It really is insignificant.

But you had a good question . . . I bet there is a setting somewhere to store the wheel size but IMO it most likely isn't necessary. The only time I've had reservations about changing tires sizes is when doing a minus 1 fitment (smaller size) for snow tires . . . always want to make sure you clear the brake harware.

Congrats on the new car...

[crug75hid]

QUOTE (6rookie09 @ Oct 24 2009, 08:47 PM)

I realize this is a very mild modification, but would appreciate some technical help. I'd like to switch out my '09 6 i Sport 16" steel wheels for the OE 17" alloy wheel with the OE tire size that comes standard on some higher trim 2009 6 models. The 17" alloy wheel was not an option on the i Sport model, and I'm not sure if that is just due to trim level packages, or if there are other technical reasons. Would doing so affect the speedometer/odometer, fuel program, ABS or DCS, or would the 17" OE wheels & tires be completely compatible? Thanks for your help.[/b]

As per my opinion, obviously the vehicle will cover more rather than the 16'' tyres, but same time you please check out the gap between the body and tyres, there shouldn't be a problem for suspension.

[edwardwitt]

QUOTE (crug75hid @ Nov 2 2009, 03:06 AM)

As per my opinion, obviously the vehicle will cover more rather than the 16'' tyres, but same time you please check out the gap between the body and tyres, there shouldn't be a problem for suspension. [/b]

Thanks much for all the thoughtful feedback. This forum is very impressive. The passion displayed for the product is refreshing, and well deserved. TRIPPP. great pic of your cluster. Where does the blue light come from? My 2009 6 does not have it. Is it standard on high trim packages, or did you add it?

[Scorch]

QUOTE (6rookie09 @ Nov 2 2009, 11:55 AM)

Where does the blue light come from? My 2009 6 does not have it. Is it standard on high trim packages, or did you add it?[/b]

It's the "EL guages" (something like that anyways) from the GT models.