Lists of TSB for Stinger found here.

[65RivieraGS]

KIA STINGER TSB This site has a nice compendium of TSB for each year of the Stinger. Fortunately, in the 60,000mi that I've put on the car, only two Warranty issues: (1) trunk visor (cargo area cover), and other being addressed today for the LHS-turbo oil feed pipe. I hope that this unit continues to be a keeper!!

 

[Snicklefritz]

https://static.nhtsa.gov/odi/tsbs/2023/MC-10242913-0001.pdf

Interesting answer to the oft-asked question, how much difference can there be to stay within spec? Answer, 10mm. What a hassle! The techs don't use a tape measure, they use a tread depth gauge. What we need is a conversion to find out how much tread depth difference is equal to 10mm circumference difference.

By the way, the Michelin staggered setup starts with the OD 2mm smaller in the rear - what that translates to as circumference difference I don't know. And the rear wears down twice as fast as the front.

 

[Thomby]

10mm or 0.4" circumference is 3.2mm or 0.13" diameter.
2mm or 0.08" diameter is 6.3mm or .25" circumference.

So about 60% of the allowable difference. It would seem like going slightly bigger in the rear would be preferable, so that they'd tend to catch up to the fronts vs. exaggerating the difference.

 

[Snicklefritz]

^^thanks! no mathfu here, or maybe mostly just lazy. 60% of the stated limit with fresh tires on? that's ridiculous. Ima guessing that KIA is erring on the side of caution. why else would they put OEM Michelin on already over half of the way there to replacement? however, by stating "10mm", they also give themselves an out if someone comes in with a trashed AWD system and worn down rear tires. they'll say, "we sent out the TSB warning, we don't owe you anything."

what's the next available rear tire OD?

edit, looked it up. it's 255/40, or 687mm, compared to 225/40 at 663mm. that's moving the other way too far.

 

[Thomby]

what's the next available rear tire OD?

edit, looked it up. it's 255/40, or 687mm, compared to 225/40 at 663mm. that's moving the other way too far.

Yes it's kind of awkward, because I would expect the natural rear tire upgrade to be 275s, but if you stick with /35 profile you go from 0.4% smaller to 1.9% bigger, and if you drop to a /30 profile you go to 2.3% smaller. Red and orange underlines below.

If you go all the way to a 285, which is getting pretty wide for an 8.5" wheel, then a /30 profile tire is 1.5% smaller (a /35 profile is 3.1% bigger). You have to go all the way to a 295 to drop to a /30 profile and get back to the original 0.4% smaller. Yellow and blue underlines below.

If you stick with a /35 profile, you can go from 255 to 265 and it'll flip you from 0.4% smaller to 0.8% bigger, and look meaty on an 8.5" wheel. Not much of an upgrade but a good match for the fronts. Pink underline below.

You could also go to 235/40 fronts and 275/35 rears to have the rears 0.8% bigger (specifically, +15mm circumference). This might be the best balance for an upgrade that keeps the sizes matched and allows for faster rear wear. Purple and red underlines below (sizes relative to 225/40).



Btw when I put the stock tire sizes into tiresize.com, it gives me a 5mm difference in circumference (vs. the 6.3 I calculated above). Seems reasonable.

 

[Snicklefritz]

You have exceeded my hopes. Thanks for that leg work. Math and I have never cooperated well.

So, if we are trying to stay within the 10mm difference for the most life of the tires, 0.8% difference, by whatever combo, creates 15mm difference starting out, but rather quickly comes within, and remains within, the 10mm difference desired. Have I got that right?