Monte Carlo Forum - Monte Carlo Enthusiast Forums - what keeps these wheels from fitting?

im still learning.....

im going to assume the gen 6 range uses a 40 mm offset wheel as "stock".
they do this on all 4 wheels so you can put them anywhere on the car.

this offset is a positive offset that moves the rim toward the car. or another way of putting it - moves the bolting surface toward the pretty side of the wheel.

the calipers and suspension coupling have to fit in the back side of the wheel and there is at least one sensor that could be a potential gotcha as well. research wheel backspace.

the 16 inch wheel/tire set is p225/60r16 with a 26.3 inch diameter tire that has a 7.2 inch tread width on a wheel with the 40 millimeter (2 5/8 inch) offset. this tire has a 9 inch section width.

the 17 inch set that are on the supercharged (high sport - fe4 option? - i need help with this) are p235/55r17 with a 9.7 inch section width and 8.3 inch wide tread on a 7.5 inch wheel. they are 6 tenths of an inch larger in diameter. (guessing stock rim width). the maximum arc of the sidewall moves away from the center of the combination - away from the strut.

(this makes me wonder if the part of the struts on the fe4 package woould be perilously close to the rim of a 16 inch wheel)

im thinking if you stay with a (p225/60r16) 26.3 inch diameter tire with a 7.2 inch tread width, you can not put a wheel without the 40 millimeter (2 5/8 inch) offset on.

the 17 inch wheels and tires are mentioned in the info about some struts saying "not for 17 or 18 inch wheels". i think that is because the section width of tires on those wheels moves closer to the strut cups.

it is just plain tight in there considering the wheel, tire and strut do move slightly throughout steering radius and suspension arc. the sidewall will move sideways as it tries to tuck laterally.

click on your favorite tire web page and dig into the specs. you can see how the tread and section width varies according to the width of the rim you stick them on. you will see how the sidewall moves with respect to the suspension. this is what makes me think the front tire options are almost restricted to 7 to 7.5 inch rims whether they are 16, 17 or 18 inches in diameter to keep the sidewall away from the struts and the rest of the tire from car parts that would damage the tire.

so i can see how some suspension components might wind up in the line of fire with different wheel diameters.

im going to get shot in the behind by people who have put different tire / wheel combinations on. i can not back up what im saying at the moment because i havent measured the components involved and cant find any gm documentation to help me.

but what other people have is real world experience - im just guessing. another variable in the equation would be using stiffer springs / struts and bumpers that dont let the excursions of the tire and / or wheel collide with the car. im going on what i can see so far by feeling around and cranking the steering from one extreme to the other and cornering hard at fun speeds in situations that make everything involved move as far as it can go :)

the only way to extend the operational turning radius and vertical arc of the front tires would be to reduce their diameter or overall width. im thinking if you added spacers or wider tires, you are going to bang into the wheel tubs and fender edges.

im throwing 19 inch or larger fittings to the wolves.

i need to research the physical difference between the fe3 and fe4 suspension package. i read a page that made it look like the fe4 was an option for the ss but standard on the supercharged models. probably fe4 is on the v8 montes too as standard. this is something to look at before selecting wheels.

what ive done so far is find out i can barely get a finger between the strut "cups" and the tires on my ss. it has 16 inch 225 60s on it - those are the official size for a 2004 ss at least.

i have taken a ruler and measured the space between the inside edge of the tread and the inside edge of the fender "lip" - around 9 inches.

(im trying to work out different wheel / tire size combinations on front and back with no chance of rubbing)

if you are still awake....

i think you have to stick with the stock geometry up front unless smaller tire diameter and wheel steering arc isnt an issue for you. again people do have their experience with different combinations that work and some that dont.

in the back there appears to be room for a tire with a 10 inch section width using a wheel with 20 mm (3/4 inch) offset and avoid the struts and the fender. the p275/40zr17 is what im using as an example. it actually has a 10.5 inch section width on an 8 inch rim.