Front backspace 17*8 on dart, final advice before buying

[purplehazenils]

Hi sorry for another wheel thread, I have searched and measured alot but I still dont feel 100% confident so im just looking for some final help before pulling the trigger on a set of wheels:
US Mag Rambler-U111 Matte Gunmetal w/Polished Lip Finish Wheels | JEGS

My car is a 1969 dart with stock front kasley hayes discs up front. I will be doing the mustang rotor conversion so the mounting surface location will be the same as stock.

The wheels I want to fit are 17*8 inch with 4.5in backspace or 0mm offset. After measuring they will fit on the back with offset shackles its just the front I am unsure about. I am hoping to run 225-235/45/17 or 225-235/50/17 on all four corners.
Heres some set ups from the "post your wheel and tire" thread as reference. Hope you dont mind me posting your pictures and specs.


---I've got 17x8 on the front 18x8 on the rear back space is 4.5 on both with 225/45/17 and 235/40/18. Stock suspension no rubbing front or rear even with the torsion bars cranked down. Think I could go a size or two wider with no problems

---coys wheels 17x7 small bolt pattern 225/50s in front and 235/50s in the back they bolted right on with no issues great wheels 4.25 backspacing

---71 Dart Swinger Showwheels 17x7 Fronts (4.25 backspace) with 215/45's and 17x8 Rears (4.5 backspace) with 235/45's

---Here is my 70 Dart. The rear is narrowed to 56 1/2" from WMS to WMS. The rear is moved back 1.25". The wheels are Ridler 695's
18x8" in the rear with 4.5" BS
255/45/18 (27" tall)
17x7" in the front with 4" BS

Now Im not sure who has changed to lbp discs which should move the mounting surface out (1/2in??) but the first car has original 5*4in discs (which I read in a different thread) and the exact same set up so Im hoping if it works for him it will work for me?
I know that with these cars different people can fit different sizes due to production but this hardly applies to the front end? Thanks in advance for any help.

 

[purplehazenils]

Went ahead and measured roughly at ride height today again this time taking pictures. Height is for a 235 45 17 tire and I made the width 240mm total, ie. 120mm out from either side of the cardboard "disc".
It clears the sway bar, tie rod etc but close on the inner fender.
What does this tell me? Possible if I trim the outer fender or not possible?

 

[racerdude5]

These are the wheels that I got for my Duster. They are 17x8 with a 5.5" backspacing. They clear everything (not sure about the sway bar, my car doesn't have one). They look great though. My tires are Kuhmo 215s (forgot the rest of the size). My front and rear wheels have different offsets and tire sizes.

Specs on the wheels are here: https://www.summitracing.com/parts/ARE-5157867

There's a picture of my car here: Walk Through The Mopar Fall Fling 2016 Show With Us - Roadkill

It's image 55 in the gallery.

 

[BigBlockMopar]

I've got 7J 17" wheels all around on my Dart.
215/50 or 225/45 is about the widest I can run front&rear.

It all also depends on your ride-height. If you like the 'no engine under the hood' 4x4-look then wider tires will probably still fit upfront.
If you want to have your car look good ;) then you're mostlikely limited to the above sizes.

I fabbed '73 Chrysler disc rotors on the original ('73) spindles which narrowed the track width by 1/4" on each side, compared to the original discbrake setup.

(The pic below shows 15" 'winter' wheels on the rear of the car. The fronts are 17").

 

[tanis4457]

I have a 67 dart, i upgraded the fronts to the 13" mustang brakes that doctor.diff sells as well as the mustang rear brake kit. I decided to run the american muscle mustang rims in 17x8 (5.72" backspace, i think). Im running 235/45/17 all around no need for spacers on the front or tie rod issues. For the rears im running a small custom 3/8" spacer to give me a little clearance and to match the hub difference between the lbp axles and the wheel hub. Im pretty sure i could fit 245/45/17 all around with this setup but i wanted to be conservative at first. The 235 tires are bridgestone potenza s04 pole position and according to tire rack measure out to 9.3 section width and 8.5 tread width.

 

[purplehazenils]

I've got 7J 17" wheels all around on my Dart.
215/50 or 225/45 is about the widest I can run front&rear.

It all also depends on your ride-height. If you like the 'no engine under the hood' 4x4-look then wider tires will probably still fit upfront.
If you want to have your car look good ;) then you're mostlikely limited to the above sizes.

I fabbed '73 Chrysler disc rotors on the original ('73) spindles which narrowed the track width by 1/4" on each side, compared to the original discbrake setup.

(The pic below shows 15" 'winter' wheels on the rear of the car. The fronts are 17").

View attachment 1715004394

Is your car very low for 215 to be max? Its kinda hard to see with the air dam, which is awesome by the way.

 

[purplehazenils]

I have a 67 dart, i upgraded the fronts to the 13" mustang brakes that doctor.diff sells as well as the mustang rear brake kit. I decided to run the american muscle mustang rims in 17x8 (5.72" backspace, i think). Im running 235/45/17 all around no need for spacers on the front or tie rod issues. For the rears im running a small custom 3/8" spacer to give me a little clearance and to match the hub difference between the lbp axles and the wheel hub. Im pretty sure i could fit 245/45/17 all around with this setup but i wanted to be conservative at first. The 235 tires are bridgestone potenza s04 pole position and according to tire rack measure out to 9.3 section width and 8.5 tread width.

Sounds like a very nice set up! I assume the doctor.diff front discs change the rotor mouting surface/position from original? Also you need a high ride height to avoid rubbing or anything?

 

[BigBlockMopar]

Just checked again today, my tires are 225/50.

My car is as low as can without it hitting stuff like the majority of speedbumps.
Has 1" torsionbars and Hotchkis adj. shocks to prevent bottoming out during 'spirited driving' ... ;)

 

[tanis4457]

Sounds like a very nice set up! I assume the doctor.diff front discs change the rotor mouting surface/position from original? Also you need a high ride height to avoid rubbing or anything?

Yes i believe the diff front discs push the mounting surface out a bit, from what ive read i think its 3/8". I never measured before and after. I dont have to run a high ride, i havent measured my fender to ground clearance but it looks in line with what im seeing other people run with similar size tires. What i did to.check the clerance everywhere was i got an unmounted mustang tire with the backspace i was looking off of ebay cheap and mounted it all around and measured from there taking in to account the tire size. Maybe theres a cheap wheel on Craigslist near you or in a junkyard.

 

[purplehazenils]

Yes i believe the diff front discs push the mounting surface out a bit, from what ive read i think its 3/8". I never measured before and after. I dont have to run a high ride, i havent measured my fender to ground clearance but it looks in line with what im seeing other people run with similar size tires. What i did to.check the clerance everywhere was i got an unmounted mustang tire with the backspace i was looking off of ebay cheap and mounted it all around and measured from there taking in to account the tire size. Maybe theres a cheap wheel on Craigslist near you or in a junkyard.

Really? It must push It out more because if your backspace is 5.72 then it would be 5.72- 3/8 = 5.345 backspace for original discs which seems like alot from what I've seen?
Unfortunately I won't be able to find any rims to use for measuring in Sweden. Was your clearances anything like the pics I posted?

 

[tanis4457]

To run bigger tires, your sway bar concerns me a little it looks awfully close. I purchased a new hellwig sway bar, that is bent back farther to allow for higher backspace rims. From what ive read the best backspace number for wider tires, is a custom number of some amount but its different for every car. Most people try and compromise and get something premade instead of custom though cause its a lot cheaper. For clearance im fine around the fenders and sway bar, im close to the tie rods but they still dont touch so i dont worry about it.

 

[purplehazenils]

To run bigger tires, your sway bar concerns me a little it looks awfully close. I purchased a new hellwig sway bar, that is bent back farther to allow for higher backspace rims. From what ive read the best backspace number for wider tires, is a custom number of some amount but its different for every car. Most people try and compromise and get something premade instead of custom though cause its a lot cheaper. For clearance im fine around the fenders and sway bar, im close to the tie rods but they still dont touch so i dont worry about it.

The picture isnt great for the sway bar it kind of tricks you, theres actually a nice bit of space between it and the wheel. So how close are you to the fenders? If you were to quickly pull into a driveway or hit a speedbump at an angle would it rub or have you grinded away the lip?

 

[purplehazenils]

Went and measured the left side as well side to be safe (last 3 pics). Its worse than the right side I think but this time it ended up being equivalent to ride height for 235 45 17 while the suspension is compressed 1cm or .39in.
The lip can be trimmed to gain about 6mm or 0.24in and I could always go down a tire size to 225 and gain another 5mm or 0.2in against the fender.
Im just not sure what an acceptable clearance to the fender is. Alot of cars look to have it really close but still is functional.

Edit: Never mentioned that with my way of measuring Im assuming that the widest part of the tire is the part that is touching the road ie. farthest from the centre which is not accurate but gives a small margin for error.

 

[McGurik]

I am curious to know the result of this. Any update?