Backspace/offset measurements

[brickyard69]

Can someone steer me towards a place that would explain where and how to take measurements for backspace and offset.

I have a 69 Camaro with a Nova 10 bolt in it. I have hung plumb-bobs from the quarter lip and inner fender well, but I need to know what to measure.

I want to run 18" wheels but I want to check sizing. I think a 10" is to wide, and most of the wheels I like do not come in 9.5, only 8 or 10.

Any help/guideance would be appreciated.

Steve

[redss86]

This should tell you what you need to know:

http://www.newstalgiawheel.com/wheelmeasurment.asp

Good Luck,
Joe

Remember to measure multiple times on both sides.:fingersx:

[brickyard69]

Does anyone have a better one?

[Midnight68]

I dont know that there is a better one than the one posted but here is another one.

http://1010tires.com/WheelOffsetCalculator.asp

http://1010tires.com/tech.asp?type=wheels

[USAZR1]

Back spacing - The measurement from the mounting pad/hub to the inner edge of the wheel.
Offset - The offset of the wheel is the distance from the mounting pad/hub to the centerline of the wheel.

Negative offset - When the mounting surface is closer to the disk/drum (Inside) of the wheel. Or the mounting pad is behind the centerline of the wheel. This type of wheel is commonly referred to as a deep-dish wheel. This offset is common in older vehicles and many of today's trucks and will bring the wheel/tire combination out away from the vehicle.
Positive offset - The mounting pad is forward of the centerline of the wheel, towards the street side of the wheel. This is common in most front wheel drive cars and some newer trucks. Generally speaking a positive offset wheel brings the wheels closer to the center of the vehicle.

[DeepBlue68]

I want to run 18" wheels but I want to check sizing. I think a 10" is to wide, and most of the wheels I like do not come in 9.5, only 8 or 10.
If you need a little more clearance for a wheel, you can try cutting/rolling the inner fender lip. Check out this thread for more info on ways to get a little more clearance for a slightly wider rear wheel/tire: https://www.pro-touring.com/forum/showthread.php?t=10840

That info is for 67-68 Camaros, but I'd imagine most of the principles will apply to a '69. A 10" wheel will definitely be pushing it though...that's pretty wide for stock wheel wells.

[brickyard69]

I have no wheels pick out yet, but I am trying to find the widest 18" I can run on a 69 Camaro.

My concern is that it has a 8.5 rear from a Nova so I don't know if I could use the same wheels as other guys.

Also, not all manufacturers make a 9" wheel. I would have to choose between an 8 or 10".

What measurements do I take?

I would guess axle flange to wheel lip. Correct?