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Discussion Starter #1
ok so im not realy a noob but no matter how much i read about what offset on wheels is i cant seem to wrap my mind around it.
so heres my problem, im looking at getting Konig Minuz's 15x6.5 +40 - i know they'll fit because ive seen someone on here with them, my question is hoe can i get them to be more flush with the fender than the stock wheels are (specifically in the back)

also a tire size recommendation would be nice and so would a brief laymans explanation of offset

thanks in advance
IAH

 

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Wheel offset calculator

IAH, check out this link - it may clarify matters. You type in your current offset and wheel width, the proposed offset and wheel width and it shows how much more (or less) the new wheel will intrude and/or extrude. It becomes an easy matter to measure :

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

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Discussion Starter #5
IAH, check out this link - it may clarify matters. You type in your current offset and wheel width, the proposed offset and wheel width and it shows how much more (or less) the new wheel will intrude and/or extrude. It becomes an easy matter to measure :

http://www.1010tires.com/WheelOffsetCalculator.asp
thnaks!

Spacers will push it out. Make sure there are enough threads for your lug nut if using slip-on spacers. I prefer bolt-on spacers or using ARP wheel studs with slip-ons.

PS: You should buy the real version of those wheels instead of knockoffs ;) Racing Hart CP-035
thanks for the tip on the spacers... as for your suggestion about buying the 'real' ones that really isnt important for me nor is it financially feasable and i dont really car to hea "well save to do it 'right'" we all have our opinions on our own cars and this isnt the first car i've modded - for now konig vs. racing hart isnt important to me. if money werent an issue at all i would be buying black 5Zigen Fn01R-c

for just a little more money, you can get some really nice wheels, with racing history, made in the UK, not knocking off another design (arguable of course) with a better width, more aggressive offset

the lower the offset, the more the wheel is "pushed" to the outside of the wheel-well

i understand what your saying its just that im not trying to go aggressive, i've always been one to stay very clean with a close attention to to detail (and yes you can argue that using replicas isnt attention to detail but i have plenty of friends who've used Konig rims with no problems)



check out

http://t3hclap.com/
http://t3hclap.com/archives/4




here's the wheel that comes to mind for you:
http://www.good-win-racing.com/Mazda-Performance-Part/61-0299.html


15X7 +25, hubcentric (because they're spec miata wheels) and black (i'm guessing you want black)


if you want to stick to "oe" size, do 205 50 15 all around. if you want slightly larger, you could do 205 55 15 front, 225 50 15 rear. both sizes are easy to find tires for.

when you get ready to mount these, please let me know, i'll do them for you.

i appreciate the offer to mount but im not exactly sure how i'd get 4 wheels and tires (not mounted) to oakland park and back in the spyder... lol
 

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despite what a few people have said, i really want to find a set of these locally to test fit, i really like the style but am not sure how they would look on my car.
http://www.good-win-racing.com/Mazda-Performance-Part/60-1042.html

http://www.good-win-racing.com/Mazda-Performance-Part/61-0367.html
these look pretty good but i'm looking for atleast a 7in wide rear to get more use out of the 225/50/15 i run

i'm also considering these http://www.good-win-racing.com/Mazda-Performance-Part/61-03217.html up front with these http://www.good-win-racing.com/Mazda-Performance-Part/61-0321.html in the rear, not completely sure on fitment but it would be nice if they fit well, I like multispoke wheels though, if I had a red/blue/white/black spyder i'd be getting that design in white.
 

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Offset is key to figure offset

OFFSET - simply the measure of distance from back of wheel hub to centerline of wheel - draw an imaganery line through center of wheel and distance from this centerline to wheel hub is the wheel's offset (usuallly a a positve number but could be negative.)

Example - If offset is "+35mm," the back of the wheel's hub is 35mm from the wheel's centerline out from centerline toward wheel well. If "-15mm offset" wheel hub would be 15mm in from centerilne toward suspension.

BACKSPACE: The Key! Distance from back of wheel hub to back of wheel.
Example - Lay a yardstick across back of wheel and measure distance from bottom of yardstick to wheel hub to get backspace. This is key because as you change wheel width you want to maintian same backspace to make sure inside of new wheel will not hit or rub against suspension parts. And since the car's engineers did a lot of work fixing backspace on stock wheel to ensure no suspension contact any new wheel, even is 1" to 2" wider wheel should mainatain this backspace.

As a result, as one evaluates wider aftermarket wheels the offset will mathamaticallly have to decrease to maintian factory correct backspace.

Example - If the stock wheel were 7" wide with a +35mm offset, going to an 8" wide wheel will result in offset decreasing by 12.5MM from +35mm to +22.5MM (discussed below) in order to maintain the original backspace of the stock wheel and avoid wheel intreferring with the suspension (I rounded 25mm = 1inch).

Confusion - the advertised width of a wheel is always measured from the inside of one of the wheel's beads across wheel to inside of opposite wheel bead -between which tire is mounted. Thus an 8" wide wheel is measuring 8" from inside bead to inside of opposite bead. However, the overall true width of such wheel is actually 9", the measurement from the outside of the wheel rim to the outside of opposite wheel rim, which takes into account the extra metal from the inside bead to the outside of the wheel lip. REMEMBER - backspace is measured from the outside of the wheel to the beginning of the hub.

POINT - the backspace of a an 8" wide wheel with a +35mm offset is not 4" plus 35mm, or 135mm [100mm - 4" x 25mm; plus 35mm]. The wheels' true overall width is actually 9" with a backspace of 147.5mm [112.5mm - 4.5" x 25mm; plus 35mm]
That is why it seems so hard to calculate offset in your head when going to wider wheels!

APPLICATION: If you want to buy a custom wheel always start with stock wheel backspace. New wheel's offset will be simply the resulting number that is left over after calculating distance from the new wheel's centerline to that portion of backspace that extends past that wheel's centerline

Example - An 7" wide stock wheel (7" from inside bead to other inside bead) with a +35mm offset will have a backsapce of 135mm as the true overall width of the 7" wheel is really 8", when properly measured from the outside of wheel lip to the outside of opposite wheel lip. This will result in the wheel having a 135mm backspace (100m - 4" x 25mm, plus the 35mm offset) To go to an 8" aftermnarket wide wheel - whose actual overall width, outside lip to outsdie lip will be 9" one must maintain the stock backspace of 135mm to allow inside of wheel to mantain its stock relationship with suspension parts. The resulting offset will be +22.5mm. Since the true centerline of the 8" aftermarket wheel is not 4" or 100mm: 50% of 8" BUT 4.5" or 112.5mm: 50% of true 9" width - to maintian the proper factroy backspace of 135mm this marketed 8-inch aftermarket wheel's offset will end up being +22.5mm [135mm backspace, less the 4.5", or 112.5mm - outside of wheel to its centerline based upon the wheel's true overall 9" width (50% of 9" , 50% of 225mm [9" x 25mm)].

Other issue when going plus size on wheels is whether new tires will grow to much in diameter or even width past inside wheel edge that serious suspension interferenece results

I found this out the hard way when having custom billet wheel made.[/SIZE]
 
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