Right now I have C6 wheels, 18x9.5 with 265/40/18 on the front and 18x10.5 with 285/35/18 for the rear.
I have searched tire sizes and most threads just show the tires from the rear. What size tires do I need on the back to get the front and rear profile the same?

 

bumb ttt

 

Running 18's u shouldve gone w/ a 35, not a 40 up front. With those sizes i would run 275/35/18 up front, and 305/35/18 out back.

 

Yea, should not have put 265-40 up front. Too tall. I have the same size wheels as you and I'm running 275-35 up front and 295-35 in the rear. Rears are .5" taller but it looks nice.

 

Front: 275/35/18

Rear: 295/35/18 or 305/35/18

 

alright thanks guys, the tires were on the wheels when I bought them. I want to replace them now but I still have a lot of tread left, no one ever notices anyway. I was just gonna go ahead and see what I need, thanks Colby.

 

The way I've always sized up tires is by converting the metric sizes to inches.
In your case, your front measures out like this, 265mm x .03937= 10.43in wide, with an aspect ratio 40% of 265, which is 265mm x .40= 106mm which = 106mm x .03937= 4.17in. With a 4.17 sidewall/profile, take 4.17 + 4.17 + 18in rim height= 26.34 total tire height. All that said, just convert to inches by multipling mm by .03937 to get inches and figure it that way. Hopes this helps!

 

Here you go I created the formulas a while ago for tire conversion info. The formulas I used are basically what's stated above. As you can see The tire specs are in Red. The Width, amount of tread height without the rim, and the total height are in yellow.

Those will be your best bets for a good look without the front wheels being taller than the backs and with the backs still being wider using the front size you have know.

 

holy eye-**** on the blue section of that chart, batman!

black lettering on dark blue is not a good combination for reading text, especially once that text is made even more fuzzy by converting a screenshot of it to a .jpg file.....light blue would have been ok, but that dark blue is bad, bad, bad.

 

My bad didn't realize it'd be that bad on other moniters. Mine shows it fine but any way here I changed the colors so it should help out a little.

 

Go to tirerack.com and find your tire and then click on "specs" it will list all the sizes made in that tire and lists width, diameter and revs per mile also. Then you can find a tire with different width but same diameter.

 

Thanks alot for the chart.

 

No prob. I was bored one day so I created it on Excel. All I have to do is plug in the tire specs and it figures everything else out for me.