Need help on wheel backspace - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**blazercrazy70** · 12-19-2012, 07:01 AM

I am looking at some 18x8 with a 4.75 backspace up front and 18x9 5.25 bs in back. Wondering what anybody thinks on tire sizes. Just looking for some suggestions.

**CC69Rat** · 12-19-2012, 08:12 AM

Tell us more about your truck. Is it dropped? If so, how much? Will it have more of a sporty feel or stock? Do you like a taller sidewall, or minimal sidewall?

What year is the truck? Leaf springs or Coils? ..

Tire size calculation:

Example - 255/50/18

255/25.4 - This gives you the width of the tire in inches. - 10.04"
255/25.4*.50 (aspect ratio) - 5.01" sidewall (from the ground to the bottom edge of the wheel)

So, 255/25.4*.50*2+rim size. 5.01*2 = 10.02"+18 This tire would be 28.02" tall overall.

Not assuming you dont know .. just trying to help.

this way you can nail it the first time. That's why I was curious how far it was dropped (if any) and how you planned to drive it (sidewall flex)

Also, do you know which rear end housing you have in your truck? It can change your backspacing around a little .. you want to make sure if you have gotten these backspacing numbers from somewhere else (?) that the two trucks have the same rear axle housing. On the numbers you posted up, I am assuming you have the late rear end. Late 70-72.

I can elaborate if you need the info.

**blazercrazy70** · 12-20-2012, 02:43 AM

Truck is a 72 coil spring rear looking at the 4/6 drop from ECE. I want the fender wells filled. I believe the 255/50 were the size I was looking at. I want the sporty look. I may have to go to the 20's to get the look I want. They are 20x8.5 with 5.25 bs.

carcollector6970 · 12-20-2012, 02:54 AM

I just finished my 72 c10 and used 18x8.5 up front with a 245/50 with 4.5bs and a 18x9.5 with a 285/40 with 4.75 bs in the rear with a 5/6 drop kit. great clearance lock to lock in front and rear. i could send you more pics if you cant tell from my profile pic. thanks todd

**blazercrazy70** · 12-20-2012, 04:45 AM

Send me some pics it looks awesome in your profile pic. What wheels did you put on it. And did you use ECE for your drop

carcollector6970 · 12-21-2012, 12:30 AM

I used Belltech 3in drop spindles and 2in springs and 6in rear c-notch and deluxe trac-bar kit from cpp the wheels are ridler 695 wheels

12-19-2012, 07:01 AM	#1
blazercrazy70 Senior Member Join Date: Sep 2006 Location: illinois Posts: 516	Need help on wheel backspace I am looking at some 18x8 with a 4.75 backspace up front and 18x9 5.25 bs in back. Wondering what anybody thinks on tire sizes. Just looking for some suggestions.

12-19-2012, 08:12 AM	#2
CC69Rat Senior Member Join Date: Jan 2011 Location: Chattanooga TN Posts: 6,206	Re: Need help on wheel backspace Tell us more about your truck. Is it dropped? If so, how much? Will it have more of a sporty feel or stock? Do you like a taller sidewall, or minimal sidewall? What year is the truck? Leaf springs or Coils? .. Tire size calculation: Example - 255/50/18 255/25.4 - This gives you the width of the tire in inches. - 10.04" 255/25.4.50 (aspect ratio) - 5.01" sidewall (from the ground to the bottom edge of the wheel) So, 255/25.4.502+rim size. 5.012 = 10.02"+18 This tire would be 28.02" tall overall. Not assuming you dont know .. just trying to help. this way you can nail it the first time. That's why I was curious how far it was dropped (if any) and how you planned to drive it (sidewall flex) Also, do you know which rear end housing you have in your truck? It can change your backspacing around a little .. you want to make sure if you have gotten these backspacing numbers from somewhere else (?) that the two trucks have the same rear axle housing. On the numbers you posted up, I am assuming you have the late rear end. Late 70-72. I can elaborate if you need the info. __________________ Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 Currently underway 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet Sold 1985 Silverado Short Fleet Sold 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride)

12-20-2012, 02:43 AM	#3
blazercrazy70 Senior Member Join Date: Sep 2006 Location: illinois Posts: 516	Re: Need help on wheel backspace Truck is a 72 coil spring rear looking at the 4/6 drop from ECE. I want the fender wells filled. I believe the 255/50 were the size I was looking at. I want the sporty look. I may have to go to the 20's to get the look I want. They are 20x8.5 with 5.25 bs.

12-20-2012, 02:54 AM	#4
carcollector6970 Registered User Join Date: Dec 2012 Location: Alfalfa Oregon Posts: 2	Re: Need help on wheel backspace I just finished my 72 c10 and used 18x8.5 up front with a 245/50 with 4.5bs and a 18x9.5 with a 285/40 with 4.75 bs in the rear with a 5/6 drop kit. great clearance lock to lock in front and rear. i could send you more pics if you cant tell from my profile pic. thanks todd

12-20-2012, 04:45 AM	#5
blazercrazy70 Senior Member Join Date: Sep 2006 Location: illinois Posts: 516	Re: Need help on wheel backspace Send me some pics it looks awesome in your profile pic. What wheels did you put on it. And did you use ECE for your drop

12-21-2012, 12:30 AM	#6
carcollector6970 Registered User Join Date: Dec 2012 Location: Alfalfa Oregon Posts: 2	Re: Need help on wheel backspace I used Belltech 3in drop spindles and 2in springs and 6in rear c-notch and deluxe trac-bar kit from cpp the wheels are ridler 695 wheels Attached Images



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