P0500 OBD-II error/freakout - tire size related (mismatched sizes)?

[Mark]

So far so good: I've put a couple of hundred km on the car with the tire size setup from Mirage #2, and no Christmas tree dashboard of death!

Also checked the brake lights (all good).

Eggman: I'm guessing this isn't a wiring problem mainly due to it occurring immediately after the wheel change, and going away after the 2nd wheel change.

Next step: stick the original tire size on the rear to confirm that here comes Santa Claus, here comes Santa Claus...

Sounds like a Mirage can handle a slight difference in tire size (front vs rear), but not an extreme tire size difference. I would guess all newer vehicles with traction/stability control & ABS would be the same way?

[Marklovski]

I have 185/65/r14 on right now and experienced no problems and had 195/50/r15 with no problems. I am looking at 185/70/r14 right now and I'm not sure if it will cause problems. Is 70 on the sidewall too big for a 14 inch rim?

[MetroMPG]

You'll only experience the type of problem described in post #1 if you have tires of 2 or more different sizes at the same time on your car, and if the size difference between them it outside the computer's happy zone.

I bet the computer itself wouldn't care if you put tractor wheels on all 4 corners, as long as they're all the same size.

Might rub, though.

[Mark]

I have 185/65/r14 on right now and experienced no problems and had 195/50/r15 with no problems. I am looking at 185/70/r14 right now and I'm not sure if it will cause problems. Is 70 on the sidewall too big for a 14 inch rim?

14" rim should have 14" tires (last two digits need to be 14).

Somewhat restating from my post #5

Tire #1 = 165/65r14 (22.4") - 14" factory tire size
Tire #2 = 175/70r14 (23.6")
Tires #3 = 185/65r15 (24.5")

Example 1 - Outside diameter variance between 185/65r15 & 175/70r14 is 3.8%.
Example 2 - Outside diameter variance between 185/65r15 & 165/65r14 is 9.4%.

The original discussion brought up different size tires being used at the same time (front vs rear). Example 1 is not creating an issue. Example 2 lit up his dash. I would assume the higher variance (of the outside diameters) of example 2 is too much for the traction/stability control &/or ABS to handle.

My guess is he could probably use tires #1 with #2 or tires #2 with #3. It's using tires #1 with #3 that may be the problem.

Changing topics somewhat -

Looking at your tire choices & comparing them to a factory 175/55r15 (22.6") tires -

175/55r14 (22.6") - 15" factory tire size
185/65r14 (23.5") variance is +4.0%
195/50r15 (22.7") variance is +0.4%
185/70r14 (24.2") variance is +7.1%.

If you want to change tire sizes, a tire installer is probably going to recommend staying with a 3% variance.

In regards to your question - As long as the width of the rim is somewhat correct, a 14" rims wouldn't care what profile tire is mounted on them. The underside of your Mirage, however, might care?

[Marklovski]

You'll only experience the type of problem described in post #1 if you have tires of 2 or more different sizes at the same time on your car, and if the size difference between them it outside the computer's happy zone.

I bet the computer itself wouldn't care if you put tractor wheels on all 4 corners, as long as they're all the same size.

Might rub, though.

Ah makes sense. I read it wrong. Do you have TPMS on both mirages? Do you think TPMS has anything to do with it?

@Mark

I was just mainly concerned about the diameter of the tire would effect the vehicle. With a variance of 4% I don't see any downsides but I do want a second opinion before I decide to move up to 7.1%.

[MetroMPG]

No TPMS on Canadian Mirages.

I think it's entirely ABS / VSS related.

[Top_Fuel]

I bet the computer itself wouldn't care if you put tractor wheels on all 4 corners, as long as they're all the same size.

I agree.

One other thing to keep in mind...

If you're running significantly taller tires, remember that your spare tire is still the diameter of the OEM tires. So if one of your front tires goes flat, you will want to put the spare tire on the rear and move one of your rear wheels to the front. That way the drive axles will have the same diameter tires. The smaller spare on the rear will probably set an ABS code, but that will only last until you get the flat tire fixed and put back on.

I'm still enjoying my 185-60-15 tires...and wondering if I should have gone even taller.

[MetroMPG]

Top Fuel: I've been watching for a used set of Ecopia EP422's ever since you posted that thread.

Surprisingly, used Mirage Enasaves come up far more often. (OK, perhaps not surprisingly.) There's a 2 year-old set of four on steelies in Ottawa for $100 right now.

[Mark]

I agree.

One other thing to keep in mind...

If you're running significantly taller tires, remember that your spare tire is still the diameter of the OEM tires.

Is it?

My spare is a 115/70r14.

115/70r14 has an outside diameter of 20.3". Factory tires are 22.4" (14") or 22.6" (15").

I wish a full size spare fit in the spare tire spot. Since I have 8 wheels for my Mirage, I would store a full spare there & toss the spare in the garage.

[Mark]

Ah makes sense. I read it wrong. Do you have TPMS on both mirages? Do you think TPMS has anything to do with it?

@Mark

I was just mainly concerned about the diameter of the tire would effect the vehicle. With a variance of 4% I don't see any downsides but I do want a second opinion before I decide to move up to 7.1%.

If Top Fuel would try 185/65r15 tires next, you would have your answer. His current 185/60r15 (23.7") tires have a 4.9% variance (compared to factory 175/55r15 tires). If he jumped to a 185/65r15, it would be a +8.4% variance.

I guess only you guys can decide if you want to do more?
​
175/55r15 (22.6") - 15" factory size
185/55r15 (23") = +1.8% variance - probably a common choice for a Mirage.
185/60r15 (23.7") = +4.9% variance - Top Fuel's current size
185/70r14 (24.2") = +7.1% variance - your consideration
185/65r15 (24.5") = +8.4% variance - most likely Top Fuel's consideration???

I will say this - 185/65r15 is a common tire size. 210 tire options on Walmart site today!

Hopefully, someone running larger tires than both of you will speak up. I just like looking at the numbers when discussing different tire sizes.