I tried to search for my answer with no provail. Going to fall asleep on my chair soon, was hoping someone could tell me the stock tire size on the Cobalt SS/SC. I'm getting new wheels and tires and I need to figure out what size tires I need to get to keep the speedo the same. Thanks guys....

Bump

I would normally just walk outside and look at my tires. My car is currently at my parents house in the garage so I can't.

 

SS/SC = 215-45-r18

I just put on 235/40zr18 and it's supposed to equal out to the same ride height

 

Thank you very much. +rep for quick reply

Looks like I'll be going with a 235/35/19

The circumference of the P215/45 x 18 original tire is 80.4816 inches

The circumference of the P235/35 x 19 aftermarket tire is 80.0363 inches

Your speedometer reading is 100.% of your true speed.

The ratio of your old vs. new tires is 1.00.

The current differential ratio is:
To retain the same overall gear ratio, you will need a differential with a 0 ratio.

Without correction, your speedometer error will be:

Indicated speed: 10 mph. Actual Speed: 9.94 mph.
Indicated speed: 15 mph. Actual Speed: 14.9 mph.
Indicated speed: 20 mph. Actual Speed: 19.8 mph.
Indicated speed: 25 mph. Actual Speed: 24.8 mph.
Indicated speed: 30 mph. Actual Speed: 29.8 mph.
Indicated speed: 35 mph. Actual Speed: 34.8 mph.
Indicated speed: 40 mph. Actual Speed: 39.7 mph.
Indicated speed: 45 mph. Actual Speed: 44.7 mph.
Indicated speed: 50 mph. Actual Speed: 49.7 mph.
Indicated speed: 55 mph. Actual Speed: 54.6 mph.
Indicated speed: 60 mph. Actual Speed: 59.6 mph.
Indicated speed: 65 mph. Actual Speed: 64.6 mph.
Indicated speed: 70 mph. Actual Speed: 69.6 mph.
Indicated speed: 75 mph. Actual Speed: 74.5 mph.
Indicated speed: 80 mph. Actual Speed: 79.5 mph.
Indicated speed: 85 mph. Actual Speed: 84.5 mph.
Indicated speed: 90 mph. Actual Speed: 89.5 mph.
Indicated speed: 95 mph. Actual Speed: 94.4 mph.
Indicated speed: 100 mph. Actual Speed: 99.4 mph.

^ Close enough.

a 245/35/19 would be the best for the speedo though. Not sure if it will fit correctly.

 

can't help you out on this one but good luck!! Let me know if the 245's end up fitting on the stock rim!!

 

^ Not sure if there was a misunderstanding. I'm getting new wheels. 19x8.5 I'm going to try and fit a 235/35/19 on it, but a 245 would be best for the speedo. It would end up being like .1 mph off.

 

245 would definately rub i think....
Im pretty sure 235s even have a little rubbing.

 

Remedy One runs 235/35/19s with no issues.

 

I don't have any rubbing issues!! i've got the falken's 235/40/18

 

I thought I heard some where,think the dealer.That more than 3% dia difference causes problems with your ABS due to programed wheel speed for the speed sensors,
Bigger means spinning slower for speed of driving.
Somthing to look into.