How much difference from a 235/45R17 from a 245/45R17 ??? I'm trying to decide on the tires for my 78 Elky. Currently the suspension is all stock, but in the somewhat near future the front end will get 2" drop spindals. The rear will stay at stock hight.

my setup is 255/40/17s on the back. i can't really say how much of a difference 10 centimeters would make on handling, but its usually a golden rule that wider is better. I have hankook k102's on the back and cargo coils on stock suspension and it handles pretty well all things considered.
the 2 inch drop spindles on the front is a great idea, i did that with the s10 spring and the car just glides.

Im running 225/45-17s front with255/40-17s on the rear i also have s10 front springs on the front and the rear is lowered 1.1/2 with ws6 springs my car handles and rides realy good.

my setup is 255/40/17s on the back. i can't really say how much of a difference 10 centimeters would make on handling, but its usually a golden rule that wider is better. I have hankook k102's on the back and cargo coils on stock suspension and it handles pretty well all things considered.
the 2 inch drop spindles on the front is a great idea, i did that with the s10 spring and the car just glides. Would the 255/40/17's fit up front with a 2" drop ??? Would it be able to turn without making contact with the fenders ??? I plan on running the same size tire on all 4 corners.

Tire/wheel fitment issues not only consider the tire size but the wheel size (width and backspacing). I know that you can use 245/45X17 tires all around on a 5th Gen with proper wheels and you might be able to go bigger. Tire size 255/40X17 on the front seems to be a stretch but maybe someone on the forum has experience with these larger tires on the front.

Tire/wheel fitment issues not only consider the tire size but the wheel size (width and backspacing). I know that you can use 245/45X17 tires all around on a 5th Gen with proper wheels and you might be able to go bigger. Tire size 255/40X17 on the front seems to be a stretch but maybe someone on the forum has experience with these larger tires on the front. Planning on using a 17x8 rim. Not sure what the propper backspacing should be. I'm thinking 4". What makes it hard is when I bought the car it had miss-matched tires on it. They're all 14's, but each one is a different size of 14. I'm leaving it parked till I can get the 17's I want. Already decided on the Centerline Galaxy rims.

Tire/wheel fitment issues not only consider the tire size but the wheel size (width and backspacing). I know that you can use 245/45X17 tires all around on a 5th Gen with proper wheels and you might be able to go bigger. Tire size 255/40X17 on the front seems to be a stretch but maybe someone on the forum has experience with these larger tires on the front. Planning on using a 17x8 rim. Not sure what the propper backspacing should be. I'm thinking 4". What makes it hard is when I bought the car it had miss-matched tires on it. They're all 14's, but each one is a different size of 14. I'm leaving it parked till I can get the 17's I want. Already decided on the Centerline Galaxy rims. Your right on the backspacing for the front rims, 4" is the best you can do imo,iam running bfg's 245/45/17's in front and 1" drop springs,and there just fine.Pay attention though to specific tire company's "sizes",they could be slightly different,because of tread patteren's or just the style of tire,but should be fine.You will love the 17's and iam glad to see more guys running bigger wheels and tires these days on there elky's,i can remember when i first did mine,alot of people said it wouldn't work,the centerline's are bitchin rims,please post some pictures once you get them on! :D