Back Space ?

[Just 1 More]

Talk to me about backspacing.. 8.8 rear with the 4 link.
Whats the sweet spot?
Rear 5.5? 5.75? 6? i've seen one with 6.5, Where's the rub point?
Front 4.5? 5? 5.5?

[RoadRacer]

But the 8.8 comes in different widths.. there’s a table in the back of the manual. That’ll affect backspace

[Just 1 More]

But the 8.8 comes in different widths.. there’s a table in the back of the manual. That’ll affect backspace

Did not know that, Thank you

[Mastertech5]

I have 10" wide wheels with 5 1/2" backspace. This will put the outer edge of the wheel about where it should land to look right in the fender. Offset is the distance from center to outside or inside of the wheel. 11" wheels should have a 6" backspace. There are charts explaining this on some of the tire/wheel websites. That's assuming you are using the standard Fox body Mustang 8.8 which are the narrowest ones. Truck 8.8s will not work, different suspension setup and they have an offset pumpkin to one side.

[Dgc333]

When I ordered my wheels I spec'd 20x10 with a 2mm offset (5.58" back space). I didn't notice until after I mounted them that one of the wheels was a 20x10 with a 35mm offset (6.88" back space). With 305/35 tires both back spaces fit with adequate clearance to the body. I wanted the deeper dish look of the 5.58" back space so I returned the other wheel. I have a Fox Body 8.8 rear end.

FWIW, the back of the build manual has a number of pictures of 33s with different size tires and wheels with the specs for each.

BTW, my wheels are American Racing "Vintage Boss" a modern twist to the classic Torque Thrust.

IMG_20220923_143020107.jpg

[Just 1 More]

What about the front, that's going to be the same on all of our cars so has any run a 18x10 with 5 BS or more? James, I forgot what you said you are running

[RoadRacer]

I have 2 sets - 19x10, 295/30r19, 19x13, 355/30r19 for road (Michelin PS4S, don’t recommend!)

so I also now have 18x12 315/30r18 hoosier a7's (slicks) for autox, but will likely use RT660 next year.

[Just 1 More]

I have 2 sets - 19x10, 295/30r19, 19x13, 355/30r19 for road (Michelin PS4S, don’t recommend!)

so I also now have 18x12 315/30r18 hoosier a7's (slicks) for autox, but will likely use RT660 next year.

Yes, BUT, Do you know what your backspace is?

[Mastertech5]

Mine are rear 18x10 with 5 1/2" backspace, fronts are 17x8 with 4 1/2" backspace and I had to add 8mm spacers on the fronts to clear the Cobra Mustang calipers (13" rotors). I will have to space my front bike fenders out 3/4" to center them over the tires. If I had used the brakes that came with the kit I would have wanted a 5" backspace on the fronts and no spacers. I hope this helps.

[RoadRacer]

Yes, BUT, Do you know what your backspace is?

Sorry my 19x10 are 7.1 backspace. My 19x13 are 9.4 backspace but I use a 2” spacer/adapter.

My 18x12 are listed as +45mm offset - you’ll have to calculate offset. I use a 1” spaceradapter for these

[Dgc333]

What about the front, that's going to be the same on all of our cars so has any run a 18x10 with 5 BS or more? James, I forgot what you said you are running

My fronts are 18x8 with 2mm offset and 4.58" back spacing with 255/40 tires

[Just 1 More]

FRom the FFR website for purchasing their rims,
Front: 18"x9" with a 5.42" backspace (24 mm offset)
Rear: 20"x11" with a 6.0" backspace (0 mm offset)

[Just 1 More]

Sorry my 19x10 are 7.1 backspace. My 19x13 are 9.4 backspace but I use a 2” spacer/adapter.

My 18x12 are listed as +45mm offset - you’ll have to calculate offset. I use a 1” spaceradapter for these

If i'm reading that right, your fronts you're running a full 7" backspace. No interference with turning radius? Hitting anything? Looks like you're at 7" on the rear also, how close to the body is that? Sorry to be picking on you the most James but, you have the set up i'm heading towards. Thanks

[Just 1 More]

Placed a straight edge on the face of the rotor and I have about 8" to the inner wheel well. 19x12 with a 6" or 6.5" BS should be fine.

[RoadRacer]

I was going to write no interference on anything but that’s not strictly true. I have no ‘stops’ so if you turn full lock the tire will graze the upper rear a-arm. I could limit the steering range to stop that but I don’t care

I’ve also played with 1” spacers to see if I can feel any difference (ffr’s numbers aren’t consistent so hard to know what “correct” offset is). But it drove the same for me so I removed them again.

As for the rear there’s a fair gap to body but I haven’t measured it and now I’m flying.. I’d guess .75-1”. But I have widest 8.8 on purpose - a 2002 Mustang GT.