Back spacing help with 15x10 Race Stars on IRS

MalcolmV8

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Hey Guys,

I did some searching on here and found people where using 15x10 with 6.5" back spacing on the IRS. Seems it requires going with a MM low profile brake line bolt and connect as well as a longer brake line, shaving down the back of the spindle and the drag link arm there as well. Not to bad.

I contacted a local dealer here in town and inquired on getting a set of rims and he's suggesting 15x10 with a 6.25" back spacing. He says that's better for brake and suspension clearance. I'm not seeing that 1/4" doing much for clearance in those places but I can see it affecting what width tire I can get away with because it might be rubbing on the IRS or the fender.

What is current advice? A lot of the threads I found in my search were really old.

Thanks
Malcolm
 

Riddick

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Not sure about race stars but my welds clear brake lines with a 5.5bs. You will have to grind knuckle regardless of what 15 inch rim you run with IRS. You will have to barely touch tie rod with a grinder too unless you ulgrade to ftbr or mm ones. Also I'm running a 26x11.5 and it clears fine. Im running a 15x9, not sure if the 10 would clear or not. Hope this helps
 
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MalcolmV8

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From my searching it seems 15x9 clears brakes lines, 15x10 requires longer brake lines as well as the low profile bolt attaching the brake line to the caliper.
I'm thinking the 5.5 back spacing is due to 15x9, 15x10 would have 6.5 to keep it in proportion?
 

I'D WIN

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Running 15x10 CCW's wrapped in 315's w/SS brake lines, two-piece Baer rotors, OEM rear IRS bolt, full FTBR kit w/toe bar end links. No grinding anywhere.
 

MalcolmV8

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Running 15x10 CCW's wrapped in 315's w/SS brake lines, two-piece Baer rotors, OEM rear IRS bolt, full FTBR kit w/toe bar end links. No grinding anywhere.

That's interesting. I wonder how your 15x10 fit past the back side of the spindle without any grinding needed. Any pics of the setup? Any idea what back spacing you have?
 

P49Y-CY

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Running 15x10 CCW's wrapped in 315's w/SS brake lines, two-piece Baer rotors, OEM rear IRS bolt, full FTBR kit w/toe bar end links. No grinding anywhere.

Very interesting, i think that's the only wheel mfr I've heard of that does not require any grinding.
 

MalcolmV8

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Yeah it's a first on me. Everyone seems to have to grind. I wonder if their rim has a bit of a recess in it where there would normally be interference?
 

I'D WIN

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I will take some photos when I get home tonight. I don't think I have anything in my cloud.
 

Givens

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I don't know of any 15's that don't require grinding the knuckle, the only wheels that dont are 16's to my knowledge.

I originally bought a set of Greg Weld wheels that were used, 15x10 6.5 BS, the knuckle requires a significant amount of grinding, but it doesn't take long. I have MM low profile banjo bolts, with brake line extensions, I also have FTBR tow links, no grinding required there. Some of the 15x10 require you to grind on the actual brake calipers.

I noticed that the wheels had small cracks next to each of the lug holes in the wheel and was scared something might go wrong. I ended up going with Billet Specialties 15x8 5.5 BS, and the brakes, nor the lines come into play with these.
 
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MalcolmV8

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I don't know of any 15's that don't require grinding the knuckle, the only wheels that dont are 16's to my knowledge.

I originally bought a set of Greg Weld wheels that were used, 15x10 6.5 BS, the knuckle requires a significant amount of grinding, but it doesn't take long. I have MM low profile banjo bolts, with brake line extensions, I also have FTBR tow links, no grinding required there. Some of the 15x10 require you to grind on the actual brake calipers.

I noticed that the wheels had small cracks next to each of the lug holes in the wheel and was scared something might go wrong. I ended up going with Billet Specialties 15x8 5.5 BS, and the brakes, nor the lines come into play with these.

That's pretty consistent with what I hear. 15x10 need low profile banjo bolt and grinding of the spindle and tow link. 15x9 and smaller seem to eliminate that hassle but I'm trying to get as much tire under there as I can so I'm leaning towards the 15x10 and getting it in there.
Just not sure what's going to be affected if I choose 6.5 or 6.25 back spacing.
 

P49Y-CY

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I will take some photos when I get home tonight. I don't think I have anything in my cloud.

yeah if you could please post up as many details as possible like backspacing, etc because it sounds like you are on a pretty much stock irs except for the toe links. I think a lot of guys would be interested in fitting a 15x10 with 315s, I know I would. ccw's are not cheap but if they really do fit that would be a nice option.

a couple years ago I emailed back and forth with billet specialties and they said they were working on 15" streetlites that would be made specifically for our irs, but I don't think it ever materialized.
 

PWORLDSTANG

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a couple years ago I emailed back and forth with billet specialties and they said they were working on 15" streetlites that would be made specifically for our irs, but I don't think it ever materialized.

Well maybe now is a good time to hit them back up and see if they can do it? I refuse to grind anything, so I'd purchase in a heart beat.

Malcolm, not to detract from your thread, but is this something you'd be open to? Clearly not a Race Star but just throwing it out there.
 

MalcolmV8

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Well maybe now is a good time to hit them back up and see if they can do it? I refuse to grind anything, so I'd purchase in a heart beat.

Malcolm, not to detract from your thread, but is this something you'd be open to? Clearly not a Race Star but just throwing it out there.

Probably not. I have no issues grinding or adjusting my car to fit parts. For me that's what it's all about. Also I'm ready now and the local guy has brand new wheels ready to go for a good price. I just have to figure out what backspacing I need.
 

04cobra88

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15x10 6.5 bs weld rts I had on my irs I grabed some mm stainless lines and still had to round off one of the he ends on the bolt to clear the rim , tie rod and knuckle , if you don't have low profile irs bolts you'll need them if you run a slick mine are 28 x10. 5 mickeys had to grind my irs bolt down , also watch the brake bleed nipple !! Mine looked close but cleared launched the car once at the track and had scraping marks inside my rims from the bleed nipple!.

Solved this issue but doing a sra swap lol
 

MalcolmV8

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15x10 6.5 bs weld rts I had on my irs I grabed some mm stainless lines and still had to round off one of the he ends on the bolt to clear the rim , tie rod and knuckle , if you don't have low profile irs bolts you'll need them if you run a slick mine are 28 x10. 5 mickeys had to grind my irs bolt down , also watch the brake bleed nipple !! Mine looked close but cleared launched the car once at the track and had scraping marks inside my rims from the bleed nipple!.

Solved this issue but doing a sra swap lol

Appreciate the feed back. I have low profile IRS bolts which ironically are taller than my stockers ground down but they look nicer lol.
SRA might be in my future but not for a while. Tired of working on the never ending project, just want to drive it for a while.
Not sure how that slick size compares. I was looking at getting some 325/50/15 MT drag radials. Buddy has those but he's SRA swapped his car so not sure if it would fit mine the same.
 

Givens

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I came back to see the pics of the 15's that didn't require grinding, still no pics.

Malcolm I'm running 15x8 with a 26x10.5 slick, the first time I was at the track and did my first burn out. I did a second gear burn out, waited till the tires pulled the rpms down, let off the brake stayed in the throttle and let the car roll forward like normal. The car hooked so hard rolling forward it ripped the gear shift out of my hand, no joke it was awesome. I wasn't expecting that.

I wanted the 10" rim also but after that I felt a lot better. I dont have any times because the only two events I went to were no times heads up that our local car club rented out the track. My car makes just shy of 800HP
 

I'D WIN

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Malcom, I stand corrected. My apologies. I had to put the car up in the air and I retract my previous statement, there was some grinding done but it wasn't done by me.
 

MalcolmV8

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Malcolm I'm running 15x8 with a 26x10.5 slick, the first time I was at the track and did my first burn out. I did a second gear burn out, waited till the tires pulled the rpms down, let off the brake stayed in the throttle and let the car roll forward like normal. The car hooked so hard rolling forward it ripped the gear shift out of my hand, no joke it was awesome. I wasn't expecting that.

I wanted the 10" rim also but after that I felt a lot better. I dont have any times because the only two events I went to were no times heads up that our local car club rented out the track. My car makes just shy of 800HP

That's pretty awesome, of course you were on a slick, i'll be on drag radials I imagine for the most part.

Malcom, I stand corrected. My apologies. I had to put the car up in the air and I retract my previous statement, there was some grinding done but it wasn't done by me.

That makes sense. I appreciate you looking into it.
 

04cobra88

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I'm not sure in regards of the drag radial to the slick , does a 325 radial fit ok on the 10 inch rim with not to much bulge ? I'd like to put a wider 18" tire on my car but it's only 18x10 fr 500s thinking on a second set of 15s lol!

Swaped to sra because I busted my gears and broke a main cap at the track with the irs
 

Givens

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i went with the slick, hoping I wouldn't break a half shaft, what DR are you gonna run? The Mickey Thompson ET street and ET street R are just like the slicks, medium soft compound is what it says on there site.
 
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