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73-87 Chevy _ GMC Trucks => Wheels & Tires => Topic started by: 75_chevy on February 10, 2014, 11:07:37 pm

Title: 15x10 4"backspacing
Post by: 75_chevy on February 10, 2014, 11:07:37 pm
stock height short bed stepside. will the 15x10 fit in the front with 275/60/15? what if I drop the front? thanks


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Title: Re: 15x10 4"backspacing
Post by: 75_chevy on February 17, 2014, 11:42:15 am
need more info?? I'll be very sad if I get the tires and everything mounted to find out if won't fit :(


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Title: Re: 15x10 4"backspacing
Post by: zieg85 on February 17, 2014, 12:28:26 pm
That is a lot of meat and with that width of rim I doubt it not rubbing even at stock height.
Title: Re: 15x10 4"backspacing
Post by: Greybeard on February 17, 2014, 02:13:43 pm
Technically the conversion makes that tire about 28" tall and just under 11" wide at the sidewall, but since this sounds like a two wheel drive I have no clue, 4 wheel drive should fit for street driving BUT some front fender trimming on the lower rear edge will probably be needed just like on all 10" wide rim tires.

Take your trusty straight edge and do some measuring with the truck on stands. One time a Looong time ago I drilled a 1x to the lug pattern and then cut it off at roughly the the length of the tire diameter and bolted it on the hub. Then turned the wheels and rotated the board and made a bunch of now more educated guesses. Need to know the backspacing of the new rims however and go from there. I suppose one could take that one step further and nail on T-sections to the ends of the board to simulate the tire width at the sidewall and tread. Lot of work though when today a tire shop should be able to look at a chart and guess

Don't know if you know this, I didn't, just found it, maybe it'll help some>>
 275/60/15=
[ (Tire Width x Aspect Ratio x 2) / 2550 + Wheel Diameter ] = 33.000
[ Tire Width / 25.4 ] = 10.826771653543307086614173228346
[ Wheel Diameter ] = 15

=33/10.83/15
Title: Re: 15x10 4"backspacing
Post by: Captkaos on February 18, 2014, 02:08:40 pm
Not sure were 2550 comes from but
275 = section width in mm.  Section width in inches = 275/25.4 = 10.82"  NOTE, this is NOT tread width.  It is the width of the tire at its widest section.  Many companies differ on this number.
60 = aspect ratio or the percentage of height based on width.  so the sidewall is 60% of the width.  165 mm or 6.496"
15 is just the rim diameter.

to get the height of the tire (roughly) in inches it is 6.496" x 2 + 15 = 27.99"
Title: Re: 15x10 4"backspacing
Post by: Greybeard on February 18, 2014, 05:24:26 pm
Nope, I don't know either, just copied and pasted the formula from a tire calculator website.

On the other hand I just went out and physically measured the tires on my Dodge which are 285/75-16. The math with the 2550 worked out to 32.764705882352941176470588235294 and they measured just over 32-1/2" physically. This is the rolling radius that I measured so the formula isn't that far off. 
So I actually did the formula in the other post WRONG anyway D'OH!
(I had the right bracket in the wrong place but it still doesn't explain why I was so far off)  ???

It should be>>>

[(275*60*2) / 2550] +15 = 27.941176470588235294117647058824

Or RDC to what you come up with.  ::)

Yeah, for a old fart college guy I can certainly screw up a wet dream....
Title: Re: 15x10 4"backspacing
Post by: 75_chevy on February 18, 2014, 05:32:36 pm
thank you guys for the info !


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Title: Re: 15x10 4"backspacing
Post by: Greybeard on February 18, 2014, 05:53:42 pm
Hey, I have some really clear mud I can sell ya.... :-[
Title: Re: 15x10 4"backspacing
Post by: Captkaos on February 18, 2014, 07:47:57 pm
By the way 275/60/15's will fit fine on a 10" rim, but it is going to cause issues if you drop the front a lot.
Title: Re: 15x10 4"backspacing
Post by: mike357 on February 25, 2014, 06:57:07 pm
I have 275/60/15s on 10"s. My front is lowered 2" and I have no issues other than occasionally rubbing slightly when going thru a  small dip at highway speeds.
Title: Re: 15x10 4"backspacing
Post by: 75_chevy on February 25, 2014, 08:29:50 pm
thank you mike what did you use to drop the front?


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Title: Re: 15x10 4"backspacing
Post by: mike357 on February 27, 2014, 07:43:40 pm
thank you mike what did you use to drop the front?


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Chopsaw. I took out the springs then cut one coil off.
Title: Re: 15x10 4"backspacing
Post by: 75_chevy on February 28, 2014, 01:33:27 pm
how's the ride


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Title: Re: 15x10 4"backspacing
Post by: mike357 on March 01, 2014, 10:15:56 pm
how's the ride


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It rides quite well. I think better than stock. The one thing to remember is to cut the rubber snubbers down as well. Otherwise you will bottom out and that is not very comfortable.
Title: Re: 15x10 4"backspacing
Post by: lukessguare on March 13, 2014, 07:32:56 pm
I'm lowered 3 up front but have 235/60/15 on 10" but wanna go a little bigger next time. But rides great an no rubbing.
Title: Re: 15x10 4"backspacing
Post by: roger97338 on March 15, 2014, 03:41:54 pm
75_chevy, I've 15x10 wheels up front, with 295/50-15 BFGs on them, and the front is lowered 3 inches. I've hit three holes in the road that were large enough that the inner lip of the front fenders cut into the tire's sidewalls. Never cut them bad enough to leak, but they were huge, ugly scars on the tires.

(http://i.imgur.com/r5SRwIQ.jpg)
Title: Re: 15x10 4"backspacing
Post by: 75_chevy on March 16, 2014, 01:48:10 am
thanks for the post roger. I'll probably have to get smaller rim and tire for the front wen I lower it because I want the front fender to come down just below the tire a little. nd that pic is of it lowered right? I guess the po of my truck lowered it because mine looks about that height too.. but I am running 15x8 w 275/60/15 so idk


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Title: Re: 15x10 4"backspacing
Post by: Captkaos on March 16, 2014, 09:50:20 am
To get the fender lip over the top of the tire with a 28" tall tire you are looking at a 5/7 drop it will work but it will hit the inner on large bumps.

This is mine with Impala SS wheels and a 4/6 drop.  They have 5.25 backspacing and are 8.5" wide.

(http://www.captkaoscustoms.com/images/sue4impss.jpg)

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
squarebody.biz

Title: Re: 15x10 4"backspacing
Post by: bake74 on March 16, 2014, 12:42:41 pm
To get the fender lip over the top of the tire with a 28" tall tire you are looking at a 5/7 drop it will work but it will hit the inner on large bumps.

This is mine with Impala SS wheels and a 4/6 drop.  They have 5.25 backspacing and are 8.5" wide.

(http://www.captkaoscustoms.com/images/sue4impss.jpg)

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
   squarebody.biz

      Hey Capt. what sizes of tires are on this truck in the picture ?
Title: Re: 15x10 4"backspacing
Post by: Captkaos on March 16, 2014, 02:08:32 pm
255/50/17 on there in that picture.

They are 275/55/17 to match the factory height.
(http://forum.73-87chevytrucks.com/smforum/gallery/2_31_03_09_5_51_25.jpeg)

Title: Re: 15x10 4"backspacing
Post by: roger97338 on March 16, 2014, 03:17:17 pm
thanks for the post roger. I'll probably have to get smaller rim and tire for the front wen I lower it because I want the front fender to come down just below the tire a little. nd that pic is of it lowered right? I guess the po of my truck lowered it because mine looks about that height too.. but I am running 15x8 w 275/60/15 so idk


You're welcome. Yes, the photo is from after it was lowered. I'm pretty sure it's 3 inches, but it might only be 2.5 inches.
Title: Re: 15x10 4"backspacing
Post by: nickz84 on March 16, 2014, 10:28:55 pm
Capt, on the front you have 275/55/17 with stock ride height do you have any rub at all ? I'm looking at a couple of options with other sized rims and I'm just trying to get opinions.
Title: Re: 15x10 4"backspacing
Post by: Captkaos on March 17, 2014, 03:36:49 pm
No rub at all with stock ride height.  They are the same height as stock, just wider.

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
squarebody.biz