17x9 on front of 78 elco

Almost anything is possible with bodywork.

275's in front is going to require inner fender surgery on any lowered G-body, unless you are just going to park it with the wheels pointing straight and not try to drive it.

The other issue with a square wheel set is that the "perfect" wheel backspacing Front/Rear isn't exactly the same. The perfect front has more backspacing (there is room inside if the wheel diameter is big enough to clear the ball joints, tie rods and control arms), while the perfect rear has less backspacing (the frame limits width), so you find the compromise widest wheel that works in both spots.

For a rotatable set on a lowered G-body without a lot of inner fender work, on a car driven on real roads, 255 is about the practical limit, and even that would fit better if the BS is optimized for the wheel position.

If your in for surgery and using spacers to get the pefect wheel location, I'm confident the right square set of 17X9's with 275's can be made to work, but it may take a lot of work.

Did quite a bit of research on this. I will be running 255 tires on 8.5x17 up fromt with 7 inches backspace. And 275 tires on 9.5x17 in the rear with 7.5 backspacing. Obviously backspacing on these wheels is wrong and according to my research i will need 2.5" adapters up front, and 3" in the rear.

I will simple try my way foreward and make my own hubcentric adapters using a lathe to get the best possible backspace. But 2.5 and 3" is what im told will make them fit in.. i dont know how turning radius will be effected though. Im guessing i can use an f41 swaybar instead of my 36mm 1le to gain a little bit..

I have fit 275/40R17s on 9.5" wheels on the front of both my Buick (sold in 2016) and MCSS without issue; albeit the Buick was trimmed more than necessary due to being youthful and having unsupervised access to cutting tools, the MCSS is completely stock up front. All had large sway bars, good shocks, and lowering springs (with high spring rates) and/or spindles. Did they rub a little at full lock? Sure. But, they worked just fine on the street and auto-x. I will be putting the same tire/wheel combo on the front of my wagon.

It is my mission in life to fit obnoxiously large tires on things. For example: those are 315s on the back of the Buick with stock frame rails, our wagon is going to have 345s with a partial frame notch, and the MCSS is going to get 390s.

Yes it possible and has been done several times before. One of the things you'll need though is a RideTech Musclebar. The "arms" on it are 3/16" thick flat stock so it provides for more tire clearance than a normal round sway bar. From what Ive been told you need to run a 4.5" backspacing 17x9 or 17x9.5 wheel. That is the largest you can use though without MAJOR surgery.

Here is some pics of a 17x9.5" Corvette Sawblade Wheel with a 275/40/17 Goodyear EAGLE F1 ASYMMETRIC at stock ride height on my 1980 El Camino. I am running a 2.75" thick, bolt on wheel adapter. The wheel itself has a 56mm offset or a total of 7.45" of backspace. Adding the 2.75" bolt on adapter, the total backspace come to 4.7" of backspace.







The only front suspension change is an addition of the speedway tubular upper A-arms with stock ball joint length.



On the front, with the suspension at full suspension droop, the driver side tire comes into contact with the brake line bracket when the steering is at full left turn lock. I don't expect to get full suspension droop anytime while I am driving, especially when taking a turn at full lock. At ride height at full left lock with all the weight on the suspension, there was no interference, as far as I could tell, on the rear of the suspension, frame, fender well, or brake line bracket.

At ride height with full weight of the car on the suspension, I did have to trim the front lower corner of the fender opening when turning the wheel to full right lock as it came close to touching. At full right turn lock, I do not remember getting any interference at full lock on the front of the suspension, frame, or A-arm. With the suspension in full droop, I do not remember getting any interference at full right turn lock on the driver side tire and wheel. I haven't drove this yet, so other tire rub may happen that I could not see.

I am only guessing here, but if you are using a drop spindle, you will gain some clearance at full droop between the brake line bracket or upper a-arms, but the tie rod will get closer to the wheel and your tire will move up and closer to the fender well.

With this wheel, tire, and 2.75" thick adapter on the rear, the tire fits perfect with stock 1980 springs and suspension pieces. There is finger distance between the frame and this tire and more than finger width between the tire and the fender lip (sorry no pictures).

Here is my buddy's old Regal: http://www.pro-touring.com/threads/...68e9587a2a278d9699e55df13&p=513097#post513097

The 17x9.5" sawblades came off of my '91 Z28 (I wasalso told that couldn't be done); I do believe the front tires he used were 255s.

I just don't think most folks are willing to put in the effort to achieve the result.

My dad had 17x8s all around with 275/40/17s on his stock '81 GP. Only suspension mods he did were air shocks in the back. THey had the wrong back spacing something crazy like 5.5 inches or something (it was the first run of Centerline Scorpion wheels, he got them for 50$ and an amplifier he had) and he had to use 5/16 spacers, because that's all he could find in the mid 1990s. With the right backspacing (4.5 is ideal with a an 8 inch rim, 9 inch should be 4.5 or less) any wheel can fit almost anything.

On the wheel side of things have you considered xxr wheels?