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15x7 vs. 15x8

  #1  
Old 02-04-2009, 11:05 PM
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Default 15x7 vs. 15x8

Ok, so... The skinny on this is that I have been looking long and hard and reading on here and I'm just plain tired of trying to find rims for my rig.

I've had a few people tell me in person that the 15x7 with 3.75 back-spacing will work with the stock 235 75r15 AT tire.

So, then I read on here that the 15x8 with 3.75of back-spacing rubs - could this be because the rim is 1" further out..?




This is the wheel I picked out as well as the rear mounted spare.
 
  #2  
Old 02-04-2009, 11:28 PM
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Default RE: 15x7 vs. 15x8

A 15x8 is only .5' wider than a 15x7...well...given the offset is close to 0, but remember, the tire is in the same spot as long as BS stays the same..youre just adjusting how wide it is at the rim

But you could probably fit 235/75s on a street tire with either of those rims, but an A/T might be cutting it close. I cleared 235/75s on 15x8s with 4.5' bs, but they were bald all-seasons. Then again, a new all-season is only like 8/32nds bigger than a bald one..

My suggestion would be to get the tire/rim combo you want, then adjust the blazer accordingly
 
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Old 02-04-2009, 11:47 PM
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Default RE: 15x7 vs. 15x8


I get what you're saying... The 7 and 8 have the same back spacing - so by thought process, this would mean that the 8 is only 1" wider on the outside right..? If this is the case, wouldn't it then, bring the outside edge in one inch compared to the 8. In point, the bulge of the sidewall, will be the same... but we're controlling the outside edge which is the part that rubs.

I've ordered the rims at no risk from the shop, and I'm going to test fit the front tomorrow.

Imagine, if we, as Blazer Fanatics, find a source for NICE alloy wheels for our trucks that WILL work with out trimming the freaking fenders!!!

OK - I'm gunna try to go to sleep now!

What's are the thoughts on the rim for this truck..?


 
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Old 02-05-2009, 07:05 AM
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Default RE: 15x7 vs. 15x8

it isnt 1" wider on the outside. It would be a 1/2" wider on the inside and the outside.
 
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Old 02-05-2009, 07:34 AM
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Default RE: 15x7 vs. 15x8

ORIGINAL: NVANZEE

it isnt 1" wider on the outside. It would be a 1/2" wider on the inside and the outside.
That would be if they were both "0 offset" wheels.


They Both have the same back-spacing of 3.75". So... From the inside lip to the hub flange is 3.75 on both the 15x7 and the 15x8 then where is the 1/2 you guys are talking about..?

The offset on the 7" is -6 (say 1/4" in from center) and the 8" is -19 (OK 3/4 in from center) the inside of the wheels are the same - even when you draw it on paper... -19 would take away the 1/2" that the wheel is wider from, and it's negative which means inside... And, if the center of the rim is relative to the half, in this case 3.5" on the 7" and 4.0" on the 8" then the wheels will be the same on the inside. Only the outside is different - by way of a deeper dish.

https://www.rsracing.com/tech-wheel.html

So, is anyone on here running 15x7's?



Don't get me wrong, I'm not trying to pick an argument but, for anyone who has shopped for wheels for these 4x4 trucks knows what an ordeal it is to get a nice wheel in a size that works!
 
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Old 02-05-2009, 08:44 AM
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Default RE: 15x7 vs. 15x8

Those are some nice rims, good choice.
 
  #7  
Old 02-05-2009, 01:47 PM
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Default RE: 15x7 vs. 15x8



I like that look! I sure hope they fit!
 
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Old 02-06-2009, 11:37 PM
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Default RE: 15x7 vs. 15x8

they rub becuase of the backspacing. Your factory tires ride inside the fenders. Less backspacing pushes the tires out into the fender wells. I haven't tried to find out what size tire you need to go down to, however I do know that stock 15x7 2wdr rims on a 4x4 will rub. 2wdr rims have less backspacing then the 4x4 versions. I believe the 2 are 4" while the 4x are 6".

Now that I think about it the '87 had 205 with the 3wdr rims and didn't rub. The 235 did rub so I had to get 4x4 rims. Swapped those out later for some Firevird 16" rims so I could mount 275/75/16 tires. Roughly 33" tires. Yes I installed a body lift and trimmed the fenders to fit the tires.
 
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Old 02-07-2009, 07:10 AM
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Default RE: 15x7 vs. 15x8

Watch for a new thread tonight, I've got to take some pictures.

The 15x7's went on like a champ and have a whopping 3/4 inch of clearance on the back side of the fender with the 235 75 r15s and no lift.

Also, with less back-spacing, the arch of the wheel, when you turn, is much wider - which can cause a rub.

The tires sit just a touch outside of the fenders giving it that Pre-Runner look everyone likes.

The guys at the tire shop did state that back-spacing doesn't change - 3.75 is 3.75 no matter the rim width, 15x8's with 3.75 back-spacing would have looked like a roller skate.

Thanks for the input guys!


 
  #10  
Old 02-07-2009, 08:20 PM
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Default RE: 15x7 vs. 15x8

I got into this so I forgot to take pictures 'till late - sorry.



Ball Joints


So this is the 15x7 with 3.75 Back-Spacing - with no rub and 235 75r15 on them.


Now with wheels...


Before shot


I realize that these are not good pictures at all so, look to see much better pics tomorrow - including the clearance maintained... and I'll take them before I start the passenger side ball joint monstrosity!









 

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