240SX wheel backspace

[mgp240]

Hi guys, I'm looking for some help on proper (AKA legal) backspace measurements for an ITA 240SX. I plan on buying Diamond Racing 15x7 for my car, but the measurement techniques are tricky enough that I'm not sure Ive got the numbers right (Hard to measure with the suspension loaded, and inacurate measurements with the weight off)
To let you know, all measurements are made considering using Hoosier 225/45
From what I can tell I would be able to barely get by with 4" BS on the front, but would need 3.5" BS on the rear. I don't want to buy 2 different wheels, so that would mean I would have to sacrifice 1" of track on the front and go with the 3.5.
Is anyone out there running Diamonds on their car & what backspace are you using?
Thanks,
Mike

[stevel]

Originally posted by mgp240@Jan 11 2006, 09:41 PM
Hi guys, I'm looking for some help on proper (AKA legal) backspace measurements for an ITA 240SX. I plan on buying Diamond Racing 15x7 for my car, but the measurement techniques are tricky enough that I'm not sure Ive got the numbers right (Hard to measure with the suspension loaded, and inacurate measurements with the weight off)
To let you know, all measurements are made considering using Hoosier 225/45
From what I can tell I would be able to barely get by with 4" BS on the front, but would need 3.5" BS on the rear. I don't want to buy 2 different wheels, so that would mean I would have to sacrifice 1" of track on the front and go with the 3.5.
Is anyone out there running Diamonds on their car & what backspace are you using?
Thanks,
Mike

[snapback]70724[/snapback]

We run custom machined Kosei K1's with a +17mm offset. For us it needs to be pushed out to clear the spring/collar on the front strut. The rear has plenty of clearance, but a wider track won't hurt either. We run the same tire and size.

steve

[mgp240]

Steve
Thanks for the info, with a +17 offset that would give approx. 4.25" BS on a 7" wide wheel, correct?
And the contact patch on the rear tires is inside the fender???

Mike

I just went to your website... would you be able to email me prices on your wheels? [email protected] Thanks

[stevel]

Originally posted by mgp240@Jan 12 2006, 05:17 PM
Steve
Thanks for the info, with a +17 offset that would give approx. 4.25" BS on a 7" wide wheel, correct?
And the contact patch on the rear tires is inside the fender???

Mike

[snapback]70788[/snapback]

Hmmm, 4.25" backspace measured from where? From the inside edge of the rim to the hub center? To tell you the truth, I'm not really sure. The rears clear just fine, no problems back there. But the lip on the front fender does need to be flattened or the tire will rub it.

Originally posted by mgp240@Jan 12 2006, 05:17 PM
I just went to your website... would you be able to email me prices on your wheels? [email protected] Thanks

you want a quote on the custom K1's with +17mm offset I assume? Shipped to what zip code?

steve

[mgp240]

I think that measurement would be from the backside lip of the rim... lay the rim, outside down on the ground and measue from a flat edge placed on top of rim... but I'm not sure either
shipping zip is 44425
also, do standard style lug nuts work with your rims, or do you need tuner style?
Thanks
Mike

[erlrich]

Originally posted by mgp240@Jan 13 2006, 04:50 PM
I think that measurement would be from the backside lip of the rim... lay the rim, outside down on the ground and measue from a flat edge placed on top of rim... but I'm not sure either
shipping zip is 44425
also, do standard style lug nuts work with your rims, or do you need tuner style?
Thanks
Mike

[snapback]70882[/snapback]

Yes - backspace is measured from the backside of the wheel. A 4.25" backspace should be equal to around a +19mm offset. All of my K-1s have a +27mm offset, and I need a 1/4" spacer to get Hoosiers to clear the front coilovers, and then they just barely do. That would mean I'm effectively running a +21mm offset, so you would be right in the ballpark with the 4.25" backspace. I also use spacers on the rears, but I don't think they ever had problems clearing without them.

[Tristan Smith]

You can also create offset with wheel spacers, as mentioned above. You will have to put in longer studs like "Moroso's", but it allows you to buy cheaper off the rack rims, without having to order special offsets. I think H&R Springs makes a set for the 240sx's.

[x-ring]

>Did you switch to the 1/2" studs, or does Moroso make a 12mm that they don't list on their website?

I don't know about Moroso, but ARP (I think) makes a long 12x1.5mm stud with the proper size knurl. Summit Racing carries them. Everybody, including NAPA, carries 12x1.5 lug nuts.

[xr4racer]

Be careful when converting backspace to offset. Someone with a 17mm offset on a 7" wheel will have approximately a 4 3/4" backspace not 4 1/4". This is because backspace takes the measurement from the back of the bolt pad to the back edge of the wheel. You will find most 7" wide wheels to be approx. 8" outer edge to outer edge, thus giving you the 1/2" difference.

Matt

[mgp240]

Steve, do you have a price on those wheels?
[email protected]
Thanks,
Mike

[stevel]

Steve, do you have a price on those wheels?
[email protected]
Thanks,
Mike
[/b]

Mike,

Sorry about this. The K1's are discontinued and Tirerack doesn't have any left in the correct size. So, tirerack will no longer be able to offer any custom bolt patterns. They would get K1 blanks from Kosei and drill them to whatever the customer needed, which we would get +17mm drilled for 4x114.3. Tirerack isn't going to get blanks in any of the newer Kosei wheels, so if it ain't on the shelf, you're outta luck. I can't believe they're doing that. Really sucks. TireRack just seems less and less appealing as the years go by.

steve

[mgp240]

Oh, I was under the impression that you guys machined them... Oh well