I am going to put 33x12.50x15's on my B2. I am planning on using 10" wide rims. Right now I have 31's on 15x7 with 4" of backspace. I amthinkin I need to lessen the backspace for the bigger tires...am I right and if so will 2 or 3 inches of backspace be good? I just want to be sure...

Thanks in advance

Later All

 

1) Are you planning on installing or have you already installed a suspension and/or body lift?
2) Are you planning on installing or have you already installed fender flares?
3) OEM wheels are usually 15x6 or 15x7 with 4.5" of backspacing. I personally wouldn't go much shallower than 4" or 3.75", but you may also wish to consider having your backspacing roughly center of the wheel width, or close to it, the reason being is you not only have to consider tire rubbing on the inside of the tire (shock, coil spring, shock/spring tower, radius arm, sway bar), but also have to consider the outside of the tire -- in your case, on the bumper and fender well opening. I have 15x8, 3.75" backspacing aftermarket wheels, and have some rubbing on the outside up front... running 30x9.50s -- although, this is probably due to alignment and ride height issues , even with the Explorer springs under mine as my top rear shackle bolts are seized in the bushings and my camber / caster is probably a little off from where it should be. Just some food for thought

 

Backspacing won't help you much w/out a lift. I have 5in susp + 2in BL and still had to cut front and rear fenderwells to clear 33s. If you have stock axles you could have issues if you go to 33s. The D28 will not hold up long, even if you baby it. A 7.5 rear will hold up for a while but again, you better not flog it. In addition to strength, another advantage of doing the D35/8.8 Sploder axle swap is that you will gain 2in of track width, a must for stability if you go as high as you need to clear 33s. And if you keep the 2.9, run low gears - 4.88 or 5.13, so you'll have enough power and can crawl slow enough. If you're willing to do all the work required to run 33s, it's well worth it.

 

He's got a D35/7.5 combination, if I recall correctly, on his '90 BII... and if I also recall correctly, those axles will handle 33s -- but I would go with 4.10 gears, personally.

 

I guess it depends on what kind of wheeling you do. For dirt/mountain roads and DD use 4.10s would prolly be fine but borderline on being just a tad too tall IMHO. 4.10s w/33s would never cut it on rocks and would most likely render top gear useless on the hiway. If you have the time & $$$ why not go w/ the 8.8 in the rear? It's wider than the 7.5 and goes well w/ the D35 + you have more locker and ratio options.

 

You can go as high as 4.56s in both axles, if you want more "go-power" off-road. If you need more than that, you can always do a doubler set-up for low-low range (6.something:1 t-case ratio is end result), or pay the big bucks for an Atlas twin-stick t-case.

http://www.4lo.com/calc/geartable.htm <-- If you're going to drive your BII at 65mph, I'll make you an appointment with those nice men in the white overcoats with that "I love me" jacket. Anyhow, 33s with 4.10s will put you around stock performance, which for me, even with my 30s, I still have some go-power in 5th (which leads me to believe that my 3.45s were swapped to 3.73s or maybe 4.10s, as my tach read higher than it should with 235/75R-15s on it, and would have been crazy high if I would have had 205/75R-15 *stock* tires on it). If you absolutely require Richard Petty speed on pavement on such a short wheelbase, topheavy, light vehicle... then go with the 4.56 gears and pray you never roll it at speed. Just my $0.10

 

armybronco2,

To answere your question on back spacing, most aftermarket wheels for our little Ford will have 3.75" back spacing. Like kernal-panic posted his 8" wheels are. You might consider the 8" wheels also if you do much playing in the rocks as it will protect the wheels from some of the rock dings.

I think 4.56's would be the way to go. I ran 4.11's on my 89 with 30" BFG AT's and an A4LD and it would avarage 20 mpg to Utah and back and walk HITR road http://www.mappyjack.com/hitr.html . 4.11's on my 88 with 33's and a C-4 is both slow starting from stop and RPM's 3,000 at 65 mph. But it has a doubler for the trail and I have another set of 235's for in town driving. What you need to do is look at your door tag and get the stock gear ratio and tire size. Then find a chart or formula to figure the new gear ratio after tire change. If you don't have access to one just post the tire size and axle code from your door sticker and I'll post the numbers and figures for you. If I used KP's info of 205's and 3.54 gears stock, 33's would require 4.22's. Now many BII's came with 205's and 3.73's. In this case I would go up to 4.56's instead of down to 4.11's

Lots of things that are not covered in that one size fits all chart. Engine size and rpm range for one. Auto tranny vs. manual for another. Overdrive tranny vs. non overdrive for another. The fact that to fit 33's you need 6" of lift and some minor fender trimming (or a massive fender trim with stock suspension). You will push a larger amount of air when going down the road at speed, and need a bit more rps to do so with the little 6 cyl (I have found they like RPMS). The larger heavier tire will take a bit more to get moving. And I ain't never, ever, in my life seen a roll over that was caused by ring and pinion ratio.

Now all that being said it depends more on the person than anything. I've seen folks that can break a hammer and do so over and over again. And I have seen others that can do just about anything with a bone stock truck. Baskin Robbins made 31 flavors of icecream for a reason. Not everyone is the same.

You will find that there are many different uses for our little trucks and many different types of folks that own them. In the end we all have to decide what is right for us and most times have to learn by doing.

Good luck with your truck. We are all just trying to help in our own way.

 

WOW! Thanks for the replys!
I ordered my wheels and tires today and went w/ the 15x10 wheels and 33"tires. I have a 4" sus lift and 3" BL so I am not too worried about clearance issues. I got a little more than 4" out ofthe sus lift. I talked to the guys at the local 4wd stores in my area and their opinions were that I wouldnt have any issues with tire rub,as far as up against the shock etc. with the 4" of backspace. Any way I wont be getting my stuff for a couple weeks but I will be sure to let you all know the deal/issues if I have any! I dont climb rocks...I mainly like riding the trails and takin on mud. I will look into the gear issue though prob after I get everything mounted and take it from there. I appreciate the advice and yes, KP...,33's are as big as I plan to go unless I swap out the axles.Thanks again everyone!
Later

 

No problem, army! Yeah, I may not go taller than 33s, and I'm even doing an axle swap (D44/9" out of an Early Bronco). At most I'll go with 35s, but I'll change the gears out if I do, or definitely go with a doubler. I prefer maintaining a fairly economical daily-driver rig, and I don't plan on going too extreme, either. On another note, I've heard that 15x8 wheels are plenty for 33s and 35s -- I've been told when you air down with the 15x10 wheels, it's easier to break a bead while off-roading. This is mostly from people who have a heavier throttle foot than me, though....

 

I have 15x10s and 33s on my F150, and I can't understand how a 15x8 would secure the bead better when aired down, as 12.50s with a 10 inch wheel have much less sidewall bend than with a 15x8.

 

That extra 2in of wheel width on a 10incher could mean the difference between holding the bead on and losing your seal, primarily when you air down for rough trails. I think 10in is too wide for a 12.50 tire below 10/12 psi on rough trails. Seen them pop beads down that low many times, but never on an 8in rim.