Help With wheel tire combo fitment!

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70Dusty440

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so wanna go 18 inch wheel on a 70 plymouth duster but wondering will a 18x8.5 with 6.25 inch backspace 1.3 inch offset running a 255/35 or a 255/40 on all 4 even fit?

stock suspension 8 3/4 rear..discs up front drums in the rear..stock spring location!
 
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70Dusty440 said:
so wanna go 18 inch wheel on a 70 plymouth duster but wondering will a 18x8.5 with 6.25 inch backspace 1.3 inch offset running a 255/35 or a 255/40 on all 4 even fit?
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Welcome to FABO!

You’re in the ballpark for sure, but we’re going to need some more information about your car to be sure.

I’m assuming you’ve upgraded to the 5x4.5” large bolt pattern, but what brakes are you running in the front? Do you have the stock upper control arms?

What rear axle do you have in the back? And what brakes? Stock spring locations?

That combo would fit on my Duster, but my Duster is pretty far from stock. I have 18x9’s with 275/35/18’s on the front and 18x10’s with 295/40/18’s in the back, but all of my suspension is aftermarket, springs are moved, etc, etc

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Welcome. First off, are you still on the stock 1970 brakes (5x4" bolt pattern) or is the car converted to larger bolt pattern 73-up brakes (5x4.5")?
 
70Dusty440 said:
large bolt pattern 5x4.5 discs front drums rear
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That helps selection of wheels but how was the conversion done? Also all methods of conversion change the track width, typically requiring the wheel to need more offset than stock.
 
dano said:
That helps selection of wheels but how was the conversion done? Also all methods of conversion change the track width, typically requiring the wheel to need more offset than stock.
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i did not do the labor on that at all lol i can tell you the rear axle is from a 1969 dana 60 and a wilwood front conversion kit
 
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70Dusty440 said:
i did not do the labor on that at all lol i can tell you the rear axle is from a 1969 dana 60 and a wilwood front conversion kit
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My suggestion then would be to figure out which Wilwood kit that you have, and the actual width of the rear axle. There are several Wilwood kits out there, and depending on the kit they're based on different spindles which changes the track width up front.

In the back, you can measure from the wheel mounting surface on the drum back to the leaf spring, as that will give us a good idea of the backspace needed. Although we'd still need to know if the leaf springs are in the stock location, relocated 3" under the frame rails, or even a 1/2" offset at the hanger/shackle.

Without that info and considering you definitely have aftermarket parts that don't necessarily match and factory specs we'd just be guessing. The Wilwood kit could be for drum or disk spindles which changes the track a lot, the rear end may be narrowed, the springs could be moved, etc.
 
72bluNblu said:
My suggestion then would be to figure out which Wilwood kit that you have, and the actual width of the rear axle. There are several Wilwood kits out there, and depending on the kit they're based on different spindles which changes the track width up front.

In the back, you can measure from the wheel mounting surface on the drum back to the leaf spring, as that will give us a good idea of the backspace needed. Although we'd still need to know if the leaf springs are in the stock location, relocated 3" under the frame rails, or even a 1/2" offset at the hanger/shackle.

Without that info and considering you definitely have aftermarket parts that don't necessarily match and factory specs we'd just be guessing. The Wilwood kit could be for drum or disk spindles which changes the track a lot, the rear end may be narrowed, the springs could be moved, etc.
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yes its been mini tubbed wilwood disc spindles kit in front..i guess i gotta do some measuring but with the mini tubbing i think have a wider selection wheel and tire wise but i want to run same size on all 4 corners ideally! im thinking a 18x8.5 with a 255 40 18 tire with a 35mm offset might be too much for the fronts? idk
 
70Dusty440 said:
im lookin at 18.5" setup all 4 corners with 6" of backspace 34mm positive offset think that will fit?
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I run 18x9's with 275's on a +35mm offset rim on the front of my Duster, but my brakes add 5mm to the track so effectively it's more like a +30 offset if you're using the '73+ disk spindles as a reference.

Whether it will work on your car though I don't know, because you still haven't told us what brake kit you're running or how wide the rear axle is. You said the car is mini-tubbed, but you didn't confirm the springs were moved 3" inboard, and you haven't measured to see if the axle is the stock width. With an A-body 8 3/4 axle width if the springs are in the stock location still a 6" backspace won't clear. If the springs are moved 3" inboard they probably will clear, but not if the axle has been narrowed to match.

I don't have a crystal ball, so, without measurements it's really hard to say.
 
72bluNblu said:
I run 18x9's with 275's on a +35mm offset rim on the front of my Duster, but my brakes add 5mm to the track so effectively it's more like a +30 offset if you're using the '73+ disk spindles as a reference.

Whether it will work on your car though I don't know, because you still haven't told us what brake kit you're running or how wide the rear axle is. You said the car is mini-tubbed, but you didn't confirm the springs were moved 3" inboard, and you haven't measured to see if the axle is the stock width. With an A-body 8 3/4 axle width if the springs are in the stock location still a 6" backspace won't clear. If the springs are moved 3" inboard they probably will clear, but not if the axle has been narrowed to match.

I don't have a crystal ball, so, without measurements it's really hard to say.
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well lets go with something standard lets say its a 73 disc brake setup can i fit 18x8.5 wheel everything else being in stock location with 34mm offset and 6" of backspace on all 4 around?
 
70Dusty440 said:
well lets go with something standard lets say its a 73 disc brake setup can i fit 18x8.5 wheel everything else being in stock location with 34mm offset and 6" of backspace on all 4 around?
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With 73+ spindles and rotors those wheels should fit in the front.

If your rear axle is stock A-body 8 3/4 width and the leaf springs are in the stock location they will not fit in the back.

But if the springs are in the stock location the mini-tub is a complete waste, because the springs are the most restrictive part.
 
72bluNblu said:
With 73+ spindles and rotors those wheels should fit in the front.

If your rear axle is stock A-body 8 3/4 width and the leaf springs are in the stock location they will not fit in the back.

But if the springs are in the stock location the mini-tub is a complete waste, because the springs are the most restrictive part.
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well my concern is the fronts and rubbing! with a 18x8.5 and a 245 40 18 or 255 35 18 setup and rubbing! dont think have trouble in the rear got 29 X 13.50-15 LT back there
 
70Dusty440 said:
well my concern is the fronts and rubbing! with a 18x8.5 and a 245 40 18 or 255 35 18 setup and rubbing! dont think have trouble in the rear got 29 X 13.50-15 LT back there
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If you have stock upper control arms that amount of backspace in the front will make it pretty close between the upper control arm and lip of the rim at full steering lock and steering extension. But I have no idea if you have stock upper control arms.

That size tire will fit easily in the front. As I’ve said 3 times, I have 275/35/18’s on 18x9’s on my car in the front. So, wider rims, much wider tires. But without knowing what brake kit you’ve got, I can’t say if that’s the right amount of backspace for YOUR car.

You should be more concerned about the back, because while you can fit a gigantic tire back there with a mini tub the backspace on the rim is very important.

Bottom line is, until you provide more information about your suspension, spring locations and brakes I can’t say for sure if any of it will fit.

Until you provide your Wilwood brake kit #, and at the very least your wheel mounting surface to spring measurement in the back, I’m done guessing and doing “what ifs”. If you have the right parts those wheels will fit. If you don’t, they won’t.
 
72bluNblu said:
If you have stock upper control arms that amount of backspace in the front will make it pretty close between the upper control arm and lip of the rim at full steering lock and steering extension. But I have no idea if you have stock upper control arms.

That size tire will fit easily in the front. As I’ve said 3 times, I have 275/35/18’s on 18x9’s on my car in the front. So, wider rims, much wider tires. But without knowing what brake kit you’ve got, I can’t say if that’s the right amount of backspace for YOUR car.

You should be more concerned about the back, because while you can fit a gigantic tire back there with a mini tub the backspace on the rim is very important.

Bottom line is, until you provide more information about your suspension, spring locations and brakes I can’t say for sure if any of it will fit.

Until you provide your Wilwood brake kit #, and at the very least your wheel mounting surface to spring measurement in the back, I’m done guessing and doing “what ifs”. If you have the right parts those wheels will fit. If you don’t, they wont
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with your car specifically in this case how is the steering with those size tires in the front how does it handle? that was a concern of mine with a 255 35/40 setup in front
 
72bluNblu said:
If you have stock upper control arms that amount of backspace in the front will make it pretty close between the upper control arm and lip of the rim at full steering lock and steering extension. But I have no idea if you have stock upper control arms.

That size tire will fit easily in the front. As I’ve said 3 times, I have 275/35/18’s on 18x9’s on my car in the front. So, wider rims, much wider tires. But without knowing what brake kit you’ve got, I can’t say if that’s the right amount of backspace for YOUR car.

You should be more concerned about the back, because while you can fit a gigantic tire back there with a mini tub the backspace on the rim is very important.

Bottom line is, until you provide more information about your suspension, spring locations and brakes I can’t say for sure if any of it will fit.

Until you provide your Wilwood brake kit #, and at the very least your wheel mounting surface to spring measurement in the back, I’m done guessing and doing “what ifs”. If you have the right parts those wheels will fit. If you don’t, they won’t.
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in his defense, too narrow is ok, he has a few options including good 3" wheelstuds with spacers, bolt on billet adapters, or using a wider axle (i.e. a stock Ranger axle being 1.5" wider, explorer axle being 2.5" wider, a B body axle being 3" wider, an XJ 8.25" being 3 3/8" wider, etc)
 
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