Fitting 17 inch rims:
I hope I'm posting this in the right place. I was able to fit 17 inch wheels on the front and back of my 82 El Camino 305 engine, stock suspension. Here's what I learned.
Front wheels
I special ordered 17 x 8 inch wheels for the front. I had ordered them with 4.5 inch backspacing because I thought I had measured correctly, but I did not. The tires were 245/45r17. With a wheel spacer (metal plate made to fit between the hub and the wheel to make better clearance) about 1/4 inch in width, the tire rubbed slightly on the rear side of the upper control arm and on the edge of the sway bar linkage (on the driver side control arm and passenger side sway bar linkage when the wheels were turned for a lefthand turn, and on the passenger side control arm and driverside sway bar linkage on a riighthand turn). Even with the spacer, I had ordered a wheel with too much backspacing. Like the advice stated previously, on the front wheels, 4 inch backspacing is the maximum you can use without rubbing issues.
How I fixed the problem:
I used a wheel adapter (similar to a wheel spacer, but uses its own set of studs to secure the wheel, ie - wheel attaches to adapter, adapter attaches to hub) I did a lot of research on many different forums (classic car, 4x4, autocross, and any other that would test the limit of wheel performance), and found that you CAN use wheel adapters safely, but they MUST be installed correctly or your wheel WILL fall off which can result in a seriuos accident and your car getting a lot of damage.
Using a wheel adapter requires the following:
-Hub stud length cannot exceed the width of the adapter
Meaning if you hub's studs are one inch from the hub to the end of the stud, then you cannot use an adapter 1 inch or thinner. This will result in your wheel being torqued unevenly against your hub's studs rather than evenly and safely against the flat surface of the adapter. There was a man on a forum that ignored this rule, it placed the weight of the car on the studs, the studs snapped off while driving, and his wheel buckled under the car.
-Get "Hub-Centric" wheel adapters
"Hub-Centric" adapters place the weight of the car on the hub, rather than placing it on the studs, by using a center bore that fits snug over your hub. Using a "lug-centric" adapter will wear your studs down and strip them out, resulting in weak studs, and, of course, your wheel falling off.
-Use proper torque specifications, don't guess.
There was a corvette guy that didn't torque his lugnuts down properly and when he went to touch the lugnuts, the studs fell off in his hands, which sucks, cause he then had to remove the studs, put new ones in (which is not fun) and start all over.
-Order good qaulity Adapters
Some grades of cheap aluminum will not hold the force of your wheel on hard turns. They can cave or warp. I would recomend billet aluminum or high grade aluminum adapters with STEEL studs. Aluminum studs (you can laugh, but they are out there) will deffinitely snap off.
-Use Acorn style, open lugnuts
Acorn (tapered at the bottom) lugnuts ensure a proper fit by centering the the stud in the hole. Flat lugnuts will not. Again, some guy used his Ford Expedition lugnuts (which are flat on the bottom and notorious for being unsafe, thay had many recalls in the 90's because of this) cause he was too lazy to go out and buy the proper ones, his will spun in an oval and . . . you guessed it, his wheel buckled under the car on the highway.
Open lugnuts allow the stud's threads to engage all the way, and some drag strips will allow you to use spacers and adapters ONLY if you have open lugnuts (so they can see that the threads are engaged), if you have lugnuts with a cap, the studs could stop at the cap, and when you torque the lugnuts down, they may torque without actually pressing the wheel against the adapter or hub, so you may think it's on all the way, but it's not.
-Do quality checks often
In some cases, there is something unforeseen, make sure you catch the problem before you accidently destroy your car and have to start all over anyway. Better safe then sorry.
If you follow these rules without exception, you should be safe. If you ignore any one of these rules, there are many examples that will prove that your wheel WILL FALL OFF!!! There's your warning.