wheel question

[carguy15102]

Actually had a question about the backspacing on these wheels. I was looking at the 18x8 size they are part number: 683-8891 on the site. It says that the backspacing for these is 40 tho. Would these work on my car even tho the factor wheels are +42? I plan on lowering it this summer also. If so what size tire would be the best to use. They also have listed these: part number 683-6791, they are a direct replacement but i'm looking to move up a size or 2. Anything you guys could tell me or any warnings you would have are appreciated. Thanks in advance.


http://www.americanracing.com/wheels/details.asp?wheelid=147&name=Casino%20Chrome&style=683&desc=1-piece%20chrome%20plated%20alloy&section=P

Edit: Link wont work you have to copy and paste it to your browser. Copy from the "http" obviously all the way to the smiley face including it.

[sudden_impulse]

Hit edit for your post and then disable graemlins, the smiley face will go away. As for the spacing on the wheels, I'm not sure. They should fit as they are extremely close, but I know nothing about the minimum/maximum backspacing for certain vehicles. But the wheels do look pretty good.

[carguy15102]

www.americanracing.com/wheels/details.asp?parent=147&wheelid=200&name=Casino%20Black&style=393&desc=1-piece%20painted%20alloy&section=

Thanks for the help on that part. Now back to the main question.

Actually had a question about the backspacing on these wheels. I was looking at the 18x8 size they are part number: 683-8891 on the site. It says that the backspacing for these is 40 tho. Would these work on my car even tho the factor wheels are +42? I plan on lowering it this summer also. If so what size tire would be the best to use. They also have listed these: part number 683-6791 which are 16's, they are a direct replacement but i'm looking to move up a size or 2. Anything you guys could tell me or any warnings you would have are appreciated. Thanks in advance.

[bballr4567]

Hmmm it will probably not matter that much all. Even though I have 18X7.5. Id try to find something might not be so close but Im not close to being an expert.

[carguy15102]

Well looks like i'm going to have to go to a wheel and tire specific store around here to get a deffinate answer. Everyone that i've asked this to has absolutely no clue. Thanks for the help tho. I'll let you guys know what I find out.

[freekLED]

Yes 8x18's with a +40 offset (backspace) will fit, BUT you may need a spacer in the rear for clearance from the strut (I think the front will be fine).

For a tire size you could use 245/35 xx18 or 245/40 xx18.
A calculator to show what the difference in diameter will do to your odometer can be found here:

www.miata.net

[SE2000]

That size will fit but if you lower it, it may burn your wheel wells

[The Artist]

backspacing has to do with the spokes clearing the caliper. The offset depends on the wheel size. As an example, the 18" wheels I had on my car last year were I think a 38mm offset, and the 19's I have now area 42mm offset. If they don't offer an application guide on the site, call them directly and ask :)

[freekLED]

^^ Good point Ray !

[carguy15102]

I got this directfrom american racing.




Offset

The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types:


Zero Offset
The hub mounting surface is even with the centerline of the wheel.
Positive
The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.
Negative
The hub mounting surface is toward the back or brake side of the wheels centerline.
"Deep dish" wheels typically have negative offset or a very low positive offset.

Calculating the Offset of a Wheel

Calculating the offset of a wheel is a fairly easy mathematical equation. First, measure the overall width of the wheel (remember, just because a wheel is 18x7.5, does not mean that the OVERALL width is 7.5”. It means that the measurement from outboard flange to the inboard flange is 7.5”). Next, divide that width of the wheel by two; this will give you the centerline of the wheel.

Overall width/2 = Centerline

After determining the centerline, measure from the mounting pad to the edge of the inboard flange (if the wheel were laying flat on the ground – face up – your measurement would be from the ground to the mounting pad). This is your back spacing.

Centerline – Back Spacing = Offset in Inches

Inches x 25.4 = Offset in mm

All of the wheels in the American Racing catalog indicate the wheel’s offset.

Determining the Right Offset for Your Car

Short of adding fender flares or a body kit to your car or rolling and pulling your fenderwells, there is no way to significantly change your car’s offset. If your car has a high offset, you will have to buy a high offset aftermarket wheel. If you car has a low offset, you will need a low offset aftermarket wheel. Typically, front wheel drive vehicles have a high offset (+35 mm or greater), and rear-wheel drive applications will have lower offsets (this is not true in all cases, as the Honda S2000 is rear wheel drive, and has a very high offset). Your installer or tire and wheel dealer should be able to tell you what the offset of your vehicle is.

The common definitions are:

Low – 0-15 mm

Mid – 16-34 mm

High – 35-40 mm

High + - 41+ mm

Other factors in determining what offset is right for your vehicle is whether not you are making any other changes to your car (lowering or raising, aftermarket brakes, etc.).

If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly.

[carguy15102]

They also offer a wheel offset calculator. Here's the link if anyone wants to see it: http://www.americanracing.com/techcenter/OffsetCalculator/offset.html

So using this and the 245/35-18 size that was suggested since its the closest in size to my stockers I came up with this. The clearance from the strut housing to the inside of the wheel will be 8mm les. And theoutside edge ofthe wheel will extend an extra 12mm.

Just figured I'd share the info that I found out. And hopefully it will help someone else. Thanks guys!