Im thinking about buying the 15x10 SS wheels on Summit for the rear but was wondering if it would look funny with 14s front and 15s rear. Id like a picture if possible. Will I be able to even see a difference with the 1" taller rim?
Also on the 15x10 wheels what would be used as a trim ring? Would the stock 14x7 trim ring work or would I have to buy another?

What backspacing is needed for a 15x10 and a 70 chevelle?

The 15x10's seem to be hard to fit a trim ring on. Whenever i find a 15x10 with the correct backspacing there is always a disclosure saying "Trim ring will not fit 15x10"

Oh, and the backspacing needs to be 5.5" Others have used 5" but it's usually not advised.

Just go with the 15 x 8
Summit also sells the correct trim ring.

The wheel center is the same for the 15" and the original 14".
With the special trim ring installed on the 15", it looks just like a 14" wheel.
I was looking at mine today from about 50' away and it looked great.

You'll want a 295-60-15 tire. Or 275-60-15.
And it will make a slug out of yor car unless you change your rear gears to 3:31-3:73
3:55 is prob best.

See this thread.
http://www.chevelles.com/forums/showthread.php?t=149273&highlight=summit+trim

I agree pretty much with Nate. I have 15x8 w. 275/60/15 tires on the back of my '69 and the stock 14x7 w. 225/60/14 on the front. Looks nice and the bigger tire on the back fills the wheelwell better, which is why I went that way. I also have 3:73 rear gears but I'm thinking about going to a higher gear for better mileage...I cruise way more than race. I think you will like the look. Also, my car has a '66 rear which is a little narrower than the '69, so tire clearance is not an issue. I prob. could have gone w. a little larger tire and still had clearance.

Duke

I agree pretty much with Nate. I have 15x8 w. 275/60/15 tires on the back of my '69 and the stock 14x7 w. 225/60/14 on the front. Looks nice and the bigger tire on the back fills the wheelwell better, which is why I went that way.
I want to do the same thing to reduce my RPMs at highway speed. Would you happen to know how much if any your cruise RPMs went down?

ttt

I had 14/15s on my old '74 camaro. Really added to the stance, but on a Chevelle, it's not the same. Camaro had a more sloped body.
http://img92.imageshack.us/my.php?image=74camarozy9.jpg

please explain why the trim rings look bad on the 15x10 wheels?

The 15x10's seem to be hard to fit a trim ring on. Whenever i find a 15x10 with the correct backspacing there is always a disclosure saying "Trim ring will not fit 15x10"

you can use a 15x8 trim ring on a 15x10 ralley wheel and it fits fine or you can buy the ralleys from wheel vintuques with the outer part chromed so no need for trim rings.

Gotago,
I have had this setup since I re-did the car so I have no comparison for you in regards to mileage. At 60 MPH, I think I'm turning betw. 3-3200 RPM (have no tach). That's why I'm strongly considering going to a higher gear (3:23-3:31). Gas isn't going to get cheaper!!

Thanks Duke, I have the stock tires and 331s and I'm turning about 2800 at 60. My speedo is probably off some but 2800 gets a tad uncomfortable on long trips.

with my 2.56s and 26" tires I turn 2500RPMs at 60 and any other speed below that because of the stall convertor im using.