markus9

I would like to run boyd smoothie 2's on the rear ,what back space would work with a 285/40/17 and 10" rim thanx!

Charged350

iTrader: (1)

prolly 5.5 or 6, dont know for sure...

Kandied91z

iTrader: (7)

depends on what you choose for the front as well as where you want it to sit on the car. i'm running 6.75 i was running 5.75 but i had rubbing issues with dr's.

markus9

What is your wheel combo as for as backspacing and wheel widths. the problem i'am having is the smoothies only come in 8 and 10" widths in 17'S what do you think will work with a 285/40/17 rear and 245/45/17 front , my 88 vert has a 1" drop and i would like to have the the tires sit flush looking down the side! your help on this would help me make up my mind!

Kandied91z

iTrader: (7)

well i'm running 8x18 front with 4.75 and in order to have the 10" rear sit flush or basically track together i'm running 6.75. this requires a very slight amount of inner fender work to smooth out some areas that may rub but it isn't anything extreme. this keeps the wheels just a hair further out from the stock location but they are inside the wheel wells.

i'm running 245/40 on the front and 285/35 on the rear so doing the same setup you would want 245/45/17 and 285/40/17. as far as offsset if you didn't want to mess with the rear you could go half of what i cut mine down. here is a picture of the rear with 5.75 backspacing.....it works but they aren't completely under the fender like the fronts and how they should be. they were alright but when i ran a 295 bfg dr i had rubbing issues on the fenders with hard driving which i didn't like so i moved them in.



see how the light shines off the rear tire....that shouldn't happen if they are completely under the fender in the right position....this may not bother some but it bothers me. now they are in the correct position and it looks 100% better.

Kandied91z

iTrader: (7)

here is a close up of what i'm talking about...this was with 5.75 backspacing which caused no inner fender issues but there was room to move them in so i did.

nolanr0413

what kind of work do you have to do to make the wheels fit, i mean do you mount the rims and tires and then jack the car up and then spin the rims to see where it rubs. I cant belive you run a 6.75 bs , i though when you run a 9.5 firehawk they come with a 5.5 bs and the fit perfectly , why would you change the bs so much just for half an inch. DO you have any pics of what you had to do to make them fit. i want to see a lot of pics of how they fit and what you had to do .

Kandied91z

iTrader: (7)

well that's alot of work your asking............yes i just mounted them and spun them to see where they rubbed, messaged a few minor areas and it was done. you can run the firehawk style but they your on a 9.5" wheel and it's sitting like the above setup. i like my wheels inside the fender like they were meant to be plus then i can set the car on the ground for shows......even with out that it looks alot better in the right location. the only way you can tell i have wide tires is from the rear which is the way it should be.

Kandied91z

iTrader: (7)

here you go...found a real good picture to explain...you can see here that they are in the well. however they aren't in line with the front and they aren't completely in the well. the change in backspacing allowed me to move them in just a bit but it was enough to really make a difference. this way they are in the well and the wheels are in line perfectly rather then having the back slightly out. even though it was roughly 1" it was 1" that was quite noticeable to me.

good luck with your project.

85TransAm406

iTrader: (1)

Ok, i'm confused, if you were running 7.75 backspacing, and are now running 6.75, wouldn't that push them further out, not in?

Kandied91z

iTrader: (7)

your right......i'm not sure what i was thinking. i just went and measured them again for the hell of it. mind has been on overload so i'll fix it. i would have had to go from a 5.75 to a 6.75. thanks for catching that! here is a good explanation for those who want to learn more about the sizing.

http://www.skulte.com/adapterfaq.html

the only thing that seems a little odd is their max backspacing requirement. if i would have went with a 6.25 i wouldn't have had to do any work to the inner fender. either way it will explain better and i fixed my numbers.

askulte

Kandied,
Just to see if I understand - you're running a 6.25" backspace in the rear with the 285's? How close is it to the bump (for the trailing arms) in the fenderwell sheetmetal, and did you need to massage it? I'll update the page if the 6.25" fits without rubbing. I was having rubbing issues under very hard cornering with race tires, the low offset 17x11 ZR1's and the poly-ended PHR at a backspace of 6.15", which is why I had some extra clearance in the calculations. I guess if you're running street tires and not pushing it and have solid heim joints in the PHR, the extra clearance isn't necessary. I think I'll update the page w/ a new max rear backspace measurement, and a note to add a little extra clearance if necessary. Thanks.

Kandied91z

iTrader: (7)

andris i'll get some pictures tomorrow of it so you can see how it sits as well as what areas are needed to clearance which is very little just so everyone can get an idea.

nolanr0413

this is great , this is like a school class, you guys are schooling me and i am seriously gonna remember this info when i decided to get rims. Someone should take all this info and make a tech info so everyone can read it and learn a thing a two .
thanks guys

askulte

Psst - Nolan! It is. Check out the link Kandied posted above, listed in the tech articles section. He he he.

The article is there for everyone's benefit, so if it's not clear, or you guys would like some more specific information to be added, let me know, and I'll do it! Thanks.

Andris Skulte

johnyIROC

I have 17X10 Boyd Magneatos on the back of mine... I went with 5.75" Backspacing, it fits, but it is close. Anything more than 5.75 and you would definitely have to do some inner fender modifications. I think 5.75" is the perfect ammount for a 10" wide rim on a thirdgen. I have 275/40 tires on them... and it is a good size.