jus checked my back spacing
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Registered User
Joined: Dec 2005
Posts: 156
From: Saddletowne AB
jus checked my back spacing
i jus measured my back spacing off my 2 18x9.5 chrome y2k rims and it came close to 7.8inches. i measured from hub mounting surface to the inner fender of the wheel (the inner lip). i believe that means it is a +65mm offset???
I need to order 2 more rims and they will be +54mm offset. What can i do with the +65mm rims? is there any remedy? should i put them in the back or front?
I hope there not useless
.. my car is a 97 z28 with sportlines. i bought the car like this (the springs r blue) also has the stock decarbon shocks.
I need to order 2 more rims and they will be +54mm offset. What can i do with the +65mm rims? is there any remedy? should i put them in the back or front?
I hope there not useless
.. my car is a 97 z28 with sportlines. i bought the car like this (the springs r blue) also has the stock decarbon shocks.
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Joined: Nov 1998
Posts: 71,122
From: Hell was full so they sent me to NJ
Take the published width of the wheel. Add 1" to that number. Subtract the backspace from that result. Multiply that number by 25.4. That is the offset in millimeters.
9.5 + 1.0 = 10.5
10.5 - 7.8" BS = 2.7"
2.7" X 25.4 = 68.6mm.
The trick is accurately measuring the width of the flange that hold the tire bead on the wheel. It can be less than 1/2" (that's where the "add 1" comes from..... 2 X 1/2" - 1.0"). If your flange width was 0.43", your backspace would be 65mm.
Using a 7/16" spacer on the 65mm wheels would make them identical to 54mm wheels.
9.5 + 1.0 = 10.5
10.5 - 7.8" BS = 2.7"
2.7" X 25.4 = 68.6mm.
The trick is accurately measuring the width of the flange that hold the tire bead on the wheel. It can be less than 1/2" (that's where the "add 1" comes from..... 2 X 1/2" - 1.0"). If your flange width was 0.43", your backspace would be 65mm.
Using a 7/16" spacer on the 65mm wheels would make them identical to 54mm wheels.
Thread Starter
Registered User
Joined: Dec 2005
Posts: 156
From: Saddletowne AB
Take the published width of the wheel. Add 1" to that number. Subtract the backspace from that result. Multiply that number by 25.4. That is the offset in millimeters.
9.5 + 1.0 = 10.5
10.5 - 7.8" BS = 2.7"
2.7" X 25.4 = 68.6mm.
The trick is accurately measuring the width of the flange that hold the tire bead on the wheel. It can be less than 1/2" (that's where the "add 1" comes from..... 2 X 1/2" - 1.0"). If your flange width was 0.43", your backspace would be 65mm.
Using a 7/16" spacer on the 65mm wheels would make them identical to 54mm wheels.
9.5 + 1.0 = 10.5
10.5 - 7.8" BS = 2.7"
2.7" X 25.4 = 68.6mm.
The trick is accurately measuring the width of the flange that hold the tire bead on the wheel. It can be less than 1/2" (that's where the "add 1" comes from..... 2 X 1/2" - 1.0"). If your flange width was 0.43", your backspace would be 65mm.
Using a 7/16" spacer on the 65mm wheels would make them identical to 54mm wheels.
I measured that flange, it seems pretty darn close to .5inch.do different wheels have different flanges? mind you that these are jus ordinary Y2K rims.
Administrator
Joined: Nov 1998
Posts: 71,122
From: Hell was full so they sent me to NJ
Yes, the width of the bead retention flange is not "standardized", but 1/2" is generally close enough.
I don't like spacers at all. Its sort of a crap shoot whether you want them on the front with the higher weight, braking and cornering loads or the rear with the high shear loads under acceleration and braking.
And, wherever you put them, you will need longer studs.
I don't like spacers at all. Its sort of a crap shoot whether you want them on the front with the higher weight, braking and cornering loads or the rear with the high shear loads under acceleration and braking.
And, wherever you put them, you will need longer studs.
Thread Starter
Registered User
Joined: Dec 2005
Posts: 156
From: Saddletowne AB
damn man, this just keeps gettin worse. how short well my studs be if i jus added the spacer and the lug nuts?
if i did get longer wheel studs, what size do you reccomend? i jus did a yahoo search and i've seen 10mm and 12mm studs.. and i read sumthing that my center caps wont fit unless i poked holes through them for the studs.
if i did get longer wheel studs, what size do you reccomend? i jus did a yahoo search and i've seen 10mm and 12mm studs.. and i read sumthing that my center caps wont fit unless i poked holes through them for the studs.
Thread Starter
Registered User
Joined: Dec 2005
Posts: 156
From: Saddletowne AB
ok I think i came up with another plan.
Keep the +65m rims and put them in the rear, and buy 2 17x8.5 Y2K's in the front. but trouble is i read the FAQ's and I need a +35 to 44mm offset. The only ones I can find on ebay and directtire.com are +56mm offset.. arrgh
Keep the +65m rims and put them in the rear, and buy 2 17x8.5 Y2K's in the front. but trouble is i read the FAQ's and I need a +35 to 44mm offset. The only ones I can find on ebay and directtire.com are +56mm offset.. arrgh
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