Spare tire / VSC question

[Smobien]

Situation:
I have 4 265/70/17 on my vehicle current. I was a cheap ass and did not replace the spare tire that is a stock 265/65/17.

Question:
What will happened if I need to use the spare tire and having a 2006 v6 (no VSC button)
How sensitive is the VSC system? Will it detect minute differences in tire rotation or does the threshold for engagement have to be pretty high?

Possible answers:
I know some of the simple answers are… well why not buy a new tire of the same size? Or do the VSC disable method? (Which I have an am just too lazy to work on)

Thank you for your input!

 

[JB.]

It shouldn't noticeably affect VSC but it could possibly subtract a little bit from VSCs ability to correct for a spin or slide.

Treat it like a temporary spare and you'll be fine.

 

[kevinpt]

i dont think it will. im getting 255/70/18's this week and now you got me thinking if i should buy a same size spare\

edit: i have an 09 so i would just put the undersized on the front and drive it with vsc turned off. you could also unplug the wire under the hood to turn all the systems off

 

[nship]

put it on and try it out then report back ,front and rear install

 

[eddiebx]

Having one wrong size spare might confuse the VSC into kicking in prematurely because it won't be reading true data at all 4 corners. For example, you have the smaller spare on the driver side and you go around a right hand curve: right off the bat the smaller spare would be spinning more due to it's smaller circumference, now compound that with the driver side wheels naturally having to spin more being on the outside edge of the turn; would these two factors add up into making the VSC think you've got excess spin on one corner as compared to the actual yaw rate collected from the sensor? No idea, lol. You guys probably have already seen how annoying it can be driving around with a mis-calibrated zero point calibration, and if I had to guess, it would probably be along the lines of that? I think using extra caution is the key here.

Another thing that comes to mind is...I read over on the 5th gen forum of a very peculiar issue caused by a mis-match tire size. I forgot who the member was, but basically he bought used tires and one of them was significantly shorter than the other 3. Anyway, he was having intermittent problems with trying to get the transfer case to unlock and go back into 2hi, brought it to the dealer and the master tech was finally able to pinpoint the issue to the mis-matched tires size. I think it was something about the different wheel spin speeds causing binding. This kind of makes sense if you think about it, when I trying to shift it out of or in to 4hi, the indicator light would blink at me forever sometimes; vs when I do as suggested and shift it while going straight ahead, I would have no problems and engagement usually only takes a matter of seconds.

So I guess also be aware of that too...

 

[Brutalguyracing]

Having one wrong size spare might confuse the VSC into kicking in prematurely because it won't be reading true data at all 4 corners. For example, you have the smaller spare on the driver side and you go around a right hand curve: right off the bat the smaller spare would be spinning more due to it's smaller circumference, now compound that with the driver side wheels naturally having to spin more being on the outside edge of the turn; would these two factors add up into making the VSC think you've got excess spin on one corner as compared to the actual yaw rate collected from the sensor? No idea, lol. You guys probably have already seen how annoying it can be driving around with a mis-calibrated zero point calibration, and if I had to guess, it would probably be along the lines of that? I think using extra caution is the key here.

Another thing that comes to mind is...I read over on the 5th gen forum of a very peculiar issue caused by a mis-match tire size. I forgot who the member was, but basically he bought used tires and one of them was significantly shorter than the other 3. Anyway, he was having intermittent problems with trying to get the transfer case to unlock and go back into 2hi, brought it to the dealer and the master tech was finally able to pinpoint the issue to the mis-matched tires size. I think it was something about the different wheel spin speeds causing binding. This kind of makes sense if you think about it, when I trying to shift it out of or in to 4hi, the indicator light would blink at me forever sometimes; vs when I do as suggested and shift it while going straight ahead, I would have no problems and engagement usually only takes a matter of seconds.

So I guess also be aware of that too...

this and if the difference is too great you are looking for serious trouble....
especially with full time 4wd vehicles

 

[Kmvreter]

I have run the spare with the similar situation (tires are one upsized) in the 16" and this was not an issue for me.
Running 265/75/16 with the original spare 265/70/16 on for over a hundred miles. No issues.