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View Full Version : Looking for help on wheel/tire size + backspacing for a 70 Chevelle SS



70-SS-502
03-01-2021, 08:54 AM
Title says it all. I've got a 70 SS that still has the original 14" rally rims & the original suspension.

I'm not looking to put the biggest wheel/tire combo but I'd like to know if I can fit Rocket Attacks 18x8 in the front & 18x9 in the rear. After reading a lot of threads on this site & others, I believe those rims will fit but I'd love to see if there's anyone on here whose run those sizes & what backspacing to use. I'm not sure on the tire size, but again, something relatively big but not the biggest as I'm not autocrossing & am looking to avoid any rubbing issues. Thanks in advance.

raustinss
03-01-2021, 02:47 PM
those sizes you will be fine , I cant give you backspacing but can tell you that you can easily fit 275s on all 4 corners and wont even come close to rubbing ( with right backspacing )

70-SS-502
03-01-2021, 08:32 PM
those sizes you will be fine , I cant give you backspacing but can tell you that you can easily fit 275s on all 4 corners and wont even come close to rubbing ( with right backspacing )

So does that mean I could run an 18x10 in the rear? My backspacing options with that rim (Rocket Attack) are 4, 4.5,5 & 5.5" front & rear. I'm thinking 4.5" bs on the front 18x9 & 5" bs on the rear as I'd like to have room for a bigger disc brake set down the road.

raustinss
03-02-2021, 02:21 PM
I'd suggest , doing a search on the largest tires you can fit . There is a chart i have seen and it had the backspacing listed . This chart had a bunch of different sizes and backspacing set ups . hell very little work and you can have 315s on the front lol
just googled something for you 18x9 (5.5" b.s) with 275/35/18 for the front and 18x10 ( 5.75" b.s ) with 305/35 drag radials is what another member was running with no problems .
so maybe a 18x10 with 5.5 bs would be just fine

csouth
03-06-2021, 07:30 PM
So does that mean I could run an 18x10 in the rear? My backspacing options with that rim (Rocket Attack) are 4, 4.5,5 & 5.5" front & rear. I'm thinking 4.5" bs on the front 18x9 & 5" bs on the rear as I'd like to have room for a bigger disc brake set down the road.

Yes you can easily run a 10" wide rear on a 70 Chevelle. Common backspacing for that would be 5.75

68Formula
03-07-2021, 06:34 AM
From others on here it seems the ideal backspacing is +6mm. That's 5.5" for a 9" wheel and 5.75" for a 10" wheel.

Couple options if you want to stick with the Rockets:

You could run 18x9s w/5.5"bs with 275/35s all around. It's a little shorter than the stock tires and since you'd be at minimum rim width for that tire, it'll feel less responsive in cornering than same tire width the on a 10" wide.
Or, you could use the 18x10s w/5.5" bs and run 265/40s on all four corners. This is closer to the stock tire height, and should still work even with the offset being .25" too shallow.

72mojave
03-14-2021, 04:37 PM
Best to measure.

Often an 18x10 with 5.75" backspace will fit the rear. But get into 285/40/18 tires and disc brakes, and you may have a problem. If you don't have discs now, don't assume you won't in the future. 18x10 with 6" backspace may be better, but check exhaust, etc. behind the tire. Every car is different, assume nothing based on what worked for someone else.

raustinss
03-14-2021, 05:31 PM
Best to measure.

Often an 18x10 with 5.75" backspace will fit the rear. But get into 285/40/18 tires and disc brakes, and you may have a problem. If you don't have discs now, don't assume you won't in the future. 18x10 with 6" backspace may be better, but check exhaust, etc. behind the tire. Every car is different, assume nothing based on what worked for someone else.

why are you suggesting more offset ? , also the exhaust on that car doesnt enter the wheel well