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post #1 of 12 (permalink) Old 04-20-2011, 06:42 AM Thread Starter
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Need Help from Wheel and Tire Specialist

Hi Guys and Gals,

I drive a 2009 LT Sedan with a 5 x 110 bolt pattern. Yesterday I purchased 4 SS rims at a steal of a price. They were used for about 5000KM as per the owner and I can tell they were not on the car long because the gold emblem is still gold. He put on 20" and put the SS rims away. The rims I bought are 18" and he said they were 9.5 inches wide. I can't find any markings on the rims indicating the size. I want to put tires on asap (Canadian Tire right now has the Goodyear Eagle GT's at buy 1 and the 2nd is half price so these are the tires I want to put on the rims) but I am not the most knowledgeable person when it comes to tires. Couple of questions... Firstly, will these rims fit on my LT Sedan? What tire size should I put on the rims. Will they rub the wheel well or suspension?

Canadian Tire's website recommends that the rim uses a 225/40ZR18 92W.

Any comments, ideas, suggestions, correct sizes (what I can use / what is best to use) would be greatly appreciated.

Thanks in advance for your help.

V-Red 09' Cobalt 2.2 Sedan
K&N Typhoon SRI, Silencer gone, Side Mouldings gone, De-Badged rear, Red Calipers, Black Drums, 17% Tint, GM Bowtie Tip, Stealth Front Turns, LED tails, 18" SS rims with GY Eagle GT rubber.
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post #2 of 12 (permalink) Old 04-20-2011, 07:05 AM
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If you are not sure, just trial fit on the front end. After installing one, turn the steering wheel complete left then complete right, have someone watching while doing that way they can see if there is any rubbing.

I think they should fit with no issues, and just use same size tire that is on the wheels now.



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post #3 of 12 (permalink) Old 04-20-2011, 07:22 AM Thread Starter
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Originally Posted by finnscobalt View Post
If you are not sure, just trial fit on the front end. After installing one, turn the steering wheel complete left then complete right, have someone watching while doing that way they can see if there is any rubbing.

I think they should fit with no issues, and just use same size tire that is on the wheels now.
Thanks finnscobalt but right now the rims are bare - no tires. I'm thinking I should just take 1 rim over to Canadian Tire and see what their tech guy says.

Still looking for feedback...

V-Red 09' Cobalt 2.2 Sedan
K&N Typhoon SRI, Silencer gone, Side Mouldings gone, De-Badged rear, Red Calipers, Black Drums, 17% Tint, GM Bowtie Tip, Stealth Front Turns, LED tails, 18" SS rims with GY Eagle GT rubber.
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post #4 of 12 (permalink) Old 04-20-2011, 08:02 AM
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Stock SS rims are not 9.5 inchs wide...LOL there 7-7.5 i believe.
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post #5 of 12 (permalink) Old 04-20-2011, 08:20 AM Thread Starter
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Originally Posted by Mkulrey13 View Post
Stock SS rims are not 9.5 inchs wide...LOL there 7-7.5 i believe.
I just went out and measured and from outside lip to inside lip is 8 inches. Not sure how they are measured but for sure they are not 9.5 inches. More like 7 inches between both lips.

Thanks Mkulrey13

V-Red 09' Cobalt 2.2 Sedan
K&N Typhoon SRI, Silencer gone, Side Mouldings gone, De-Badged rear, Red Calipers, Black Drums, 17% Tint, GM Bowtie Tip, Stealth Front Turns, LED tails, 18" SS rims with GY Eagle GT rubber.
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post #6 of 12 (permalink) Old 04-20-2011, 05:05 PM
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If the rims are silver painted and have about 10 spokes like this:



Then they are 18x7.5 (Meaning they're 7.5 inches wide). These are the SS/TC rims. They come stock with 225/40R18. For tire choice, you can go with the stock size. 235/40R18 should work fine (They work fine on the SS/SC rims, and those are only 7"), and some people have even used 245/40R18 on the SS/TC rims.

If your rims are more like mine:



Then they're 18x7". The stock tires on those are 215/45R18, but many of us SS/SC guys run either 225/40R18 or 235/40R18.

Just a word of caution: Changing your tire size will cause some error in your speedometer reading unless you get it recalibrated.


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Last edited by Nighthawk243; 04-20-2011 at 05:08 PM.
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post #7 of 12 (permalink) Old 04-20-2011, 09:40 PM
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This should apply to all years Cobalt. Factory wheel sizes only.
  • 15 inch - 15x6
  • 16 inch - 16x6
  • 17 inch - 17x7
  • 18 inch - 18x7.5

As far as I know, wheel sizes are measured from inner beads across, so the inside of one lip to the inside of the opposite lip in a perpendicular, straight line.

As for tire sizes, I would not go over 25.5" tall or 8.85" wide on any wheel, but larger will fit (sorta).

Some ideas of how big a tire is as follows (general dimensions, not precise):

215/35-18 = 8.5" wide and 24" tall (mounts on 7-8.5" wheels correctly)

225/45-18 = 8.85" wide and 26" tall (mounts on 7-9" wheels correctly)

225/40-18 = 8.85" wide and 25" tall (mounts on 7.5-9" wheels correctly)

235/40-18 = 9.25" wide and 25.5" tall (mounts on 8-9.5" wheels correctly)

245/40-18 = 9.65" wide and 25.7" tall (mounts on 8-9.5" wheels correctly)


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post #8 of 12 (permalink) Old 04-21-2011, 12:58 PM Thread Starter
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Quote:
Originally Posted by Nighthawk243 View Post



Then they're 18x7". The stock tires on those are 215/45R18, but many of us SS/SC guys run either 225/40R18 or 235/40R18.

Just a word of caution: Changing your tire size will cause some error in your speedometer reading unless you get it recalibrated.
Those are what they look like (5 spoke). Thanks to all for the input. Today I purchased and had mounted 4 Goodyear Eagle GT's size 225/40ZR18 92W - They look awesome. According to their tire size selector, these tires only put the speedometer out 0.8% - very low change so not to worried about recalibration. They are also filled with Nitrogen (added bonus).

Again, thanks to all who responded. Putting them on the car on Saturday so I will post some before and after pics.

V-Red 09' Cobalt 2.2 Sedan
K&N Typhoon SRI, Silencer gone, Side Mouldings gone, De-Badged rear, Red Calipers, Black Drums, 17% Tint, GM Bowtie Tip, Stealth Front Turns, LED tails, 18" SS rims with GY Eagle GT rubber.
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post #9 of 12 (permalink) Old 04-24-2011, 01:54 PM Thread Starter
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Pics - B4 and after... repainted the calipers while I had the rims off. Drives like a dream on these 18's with Goodyear GT rubber. Happy camper

Before...


After...

V-Red 09' Cobalt 2.2 Sedan
K&N Typhoon SRI, Silencer gone, Side Mouldings gone, De-Badged rear, Red Calipers, Black Drums, 17% Tint, GM Bowtie Tip, Stealth Front Turns, LED tails, 18" SS rims with GY Eagle GT rubber.
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post #10 of 12 (permalink) Old 04-24-2011, 02:43 PM
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Quote:
Originally Posted by Rubberdude88 View Post
Pics - B4 and after... repainted the calipers while I had the rims off. Drives like a dream on these 18's with Goodyear GT rubber. Happy camper

Before...


After...
those look awesome on your car!! great find!
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