Originally posted by TheShibbster
Ok I've been lookin at aewheels and was wondering...if i bought a wheel from them that has a +27mm offset would that be alright? I see their wheels on mazdas online all the time so I have to ask...because I just really like their wheels and they aren't that bad on prices. Anyway help would be great...i'm look at series 203 17x8 with the +14offset, series 219 18x8 and 20x8 +27offset, series 212 17x8 +27offset. Mind you my truck will not be tuckin just lowered 3" in the front and 4" in the back. Apparently the stock wheel offset on a mazda is +08mm so it says on the
www.fastco.ca website app guide...so im goin off that and the +31 offset on the denali's and escalades...for the wheels with +27offset from aewheels.
Thanks guys!
You are making the same mistake everyone lese makes. They say "well, I know a +31 fits, so a +37 has got to fit too" (just numbers I picked at random, has nothing to do with what fits mazdas)
But, ifthe +30 is a 7 inch wide wheel, and the +37 is an 8.5 inch wide wheel, the +37 will end up sticking out.
Let me help you:
"the stock wheel offset on a mazda is +08mm"
forget about that. That is for a 6 inch wide wheel. It doesnt mean you only need +8mm offset to tuck. It means that if you have a 6 inch wide wheel, you only need +8mm offset to tuck like a factory wheel, which is a HELL of a lot more than is required, I think on a 6 inch wheel you only need +19 or 20mm.
Ther reason why, is because offset is measured from the wheel centerline. Every time you add width to a wheel though, the wheel centerline stays where it is and the extra width is split over each side. SO if you go from a 7 inch wide to an 8 inch wide, the center is still in the middle of the rim but now there is an extra half inch of rim on the backside, and an extra inch on the front side. If your wheels just barely tucked, what will an extra half inch added to the outside of the rim do?
Now you need to know how to calculate backspace from offset. Backspace is ALWAYS measured from the back lip of the rim to the mounting surface. More important than backspace for tucking though is frontspace. you get frontspace by subtracting backspace from the overall width.
A quick note on wheel width. A 6 inch rim is actually 7 inches wide. A 7 inch rim is actually 8 inches wide. The mountng bead adds a half inch to each side of the rim. So when you are talking about offset, its not as important to add this inch (because offset is measured from the centerline) but for backspace it is of PARAMOUNT IMPORTANCE to remeber this.
SO lets take a wheel we KNOW FOR SURE will fit without rubbing on a Mazda. A 7 inch wide wheel with +32 offset will fit both the front and the back of a mazda truck without rubbing the fenders.
7 inches wide + an inch for beads (we want to know the backspace, need to add this inch) = 8 inches, this is the overall width. Half of this measurement is the centerline, 4 inches. Add 32mm to 4 inches...
oops. Cant do that. Need to convert mm to inches. 1 inch = 25.4 mm, so if we divide 32 by 25.4, we get 1.259 inches, for clarity lets say 1.25. Therefore the backspace on a +32 7 inch wide wheel is 5.25 inches, a proven measurment that will tuck on a mazda.
So how do we translate this number to different widths? By taking the frontspace measurement. Frontspace CANT change and still tuck. 7 inch wide + the bead inch = 8 inches, minus the backspace of 5.25 = 2.75. We cant go beyond this number without being in danger of rubbing the fender lips.
You mentioned an 8 inch wide wheel with +27 offset. We can use this frontspace measurement to help us see where the rim edge would sit. 8 inches wide plus the beads = 9 inches. We have to have a frontspace of 2.75, so 9 inches minus the frontspace will give us the required backspace, 6.25. You will see easily that the extra inch of width from going from 7 inches wide to 8 all has to be on the back half of the rim in order to still tuck.
To find what 6.25 backspace means in offset, we reverse the process, take the overall width, 9 inches, and divide in half, 4.5 inches is the wheel centerline. Subtract this from the backspace, 6.25 - 4.5 = 1.75 inches. This is the offset needed to tuck with an 8 inch wide wheel. You can see this is exactly 1/2 inch more offset than the 7 inch wide wheel, which makes perfect sense, because the backspace increased an inch and the back half of the wheel increased by a 1/2 inch. 1 - 1/2 = 1/2 increase in offset. Take 1.75 and multiply it by 25.4 = 44.45 or rougly 45mm offset needed to tuck an 8 inch wide wheel.
you said you have +27 8 inch wide wheels. 45mm-27mm = 18mm further they will stick out, or roughly 3/4 of an inch. They will not tuck in the rear, likely be even with or slightly past the fender edge. Camber in the front will help tuck.
+14 on an 8 inch wide would be even worse, roughly 30mm or 1.25 inches past tucking. I doubt even camber would help tuck those.
Hope this helps. You can figure any required offset for any width by using the steps I outlined above. Remember, OFFSET MEANS NOTHING WITHOUT WIDTH. A +31 7 inch wide wheel will tuck no problem, a +31 7.5 inch wide escalade wheel means you need to flare the fenders. Same offset, different widths, different backspaces, different fit.