i had a flat last weekend right rear and all my tires are bold,order new set of tires
in the mean time i got to work and there is a decent tire that has 3 plugs from
370z 245/45/18 so i figure i'll use it till i get my tires i order,put them in the rear two tires on the way home "s-awc service light come on" at the light restart car light went off after 1 mile or so s-awc light comes back again,my question is this is because of the tires i put on that is different profile 45 instead of 40,and i cant put back the oem tires anymore cause the junk guys took from the shop.do guys have any idea?

 

Don't drive your AWD car with mismatched tires.

 

<= That's approximately the face I made when I read this: "370z 245/45/18 so i figure i'll use it till i get my tires"

You will ruin your drivetrain if you drive on those tires. On an AWD car it is imperative that they all have the same height. This is why if you get a flat on even a slightly worn tire, you're supposed to replace all 4. Even the small differences between a new and worn tire of the same size can cause damage. It's also why on a car so concerned with weight, we have a full-size spare tire... which is what you should have put on.

 

Yep. Roll around on your spare on the rear until your new tires get in.

 

Unfortunately, it sounds like that's not an option now since the scrap yard took his two rear tires.

OP, your only real option is to not drive it until your tires come in. Personally, I'd have it towed to the shop for installation, but since the damage may already be done (service light is on), it's up to you if you want to just drive it over.

 

What are you talking about, all I have in the trunk is a donut, not a fifth full size rim and tire. I know the circumference matches, but that's about it.

 

A lot of spare tires are of smaller diameter than the service wheels/tires, but ours matches up pretty closely.

Looks funny to me, seeing a big 18" skinny spare in the trunk.

 

You need to most definitely replace the tires like now. You're S-AWC cannot function properly and your drivetrain will be ruined if you continue to drive on uneven sized tires. All 4 tires must have the same circumference on an AWD car.

 

Yup, that's it. In my shock, perhaps I went overboard on the "full-size" comment. All I was referring to is that the spare is the same diameter as stock wheels, which is very rarely the case on modern sedans and coupes.

 

i heard different tire size can ruin your transmission. Better not do it for long run.