Tire setup question

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OCD4B2
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Tire setup question

Post by OCD4B2 » Tue Jun 14, 2005 1:46 am

Ok I am putting a 4 inch lift on my Bronco II soon and I just wanna get everything set up right. Here it is:
33x12.50x15 Super Swamper TSL's
15x8 black rock krawler rims


I know that everyone says 15x10's are bad on the wheel bearings but I was just wondering the facts. Also, what is the stock backspacing? I have a regular ass 7.5 in the rear and a dana 35 in the front..... What are the details? :hmmm:
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marinebroncoii
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Post by marinebroncoii » Tue Jun 14, 2005 4:57 am

I had some 33x12.5s on some 7 inch rims (not recommended and most places wouldn't even mount them) I don't know what backspacing I had but it was close to stock. I never wore out any wheel bearings, and before that my dad had the same tires and rims on his truck without any problems. 15x10 rims aren't harder on the wheel bearings, it is the offset the gets hard on them, the spindle is designed to balance the load onthe wheel bearings with the stock offset and rims. If you had 6 inch rims with 3 inches of backspacing to keep it equal to the stock setup as far as how the weight is distributed on the inner and outer wheel bearings you would want to get 8 inch rims with 4 inch backspacing or 10 inch rims with 5 inches of back spacing. I'm not sure what stock backspacing is but that is just an easy example. Even if you don't have it match the stock setup and you throw off the balance some it isn't going to make your bearings go bad all that quick. Any oversize tire, or wider rim setup is going to throw things off some and be a little harder on the wheel bearings, but not enough to cause the to destruct overnight, you will just want to keep an eye on them and you hear a rattle up front or when you jack the truck up there is play in the wheel (you can wiggle it some and usually hear the worn bearings make noise) then go ahead and replace them. If it is the outer wheel bearing you can tighten the spindle nut some and get away with the old ones a little longer. 12.5s look better on 10 inch rims, it will make them appear wider and there will be less bulge in the sidewall. The only time I can see wide offset rims being dangerous on a truck is if you went crazy and had almost no backspacing or negative backspacing like a dually rim. Adapters are also not a good idea with rims with very little backspacing, other than that the wheel bearing will be fine, but will wear out faster than if you had a stock setup.
8-9" susp, 3" body lift, 39.5x16 TRXUS STS, 342 stroker, C6, NP205, D44HD mini spool-coil sprung, D60 limited slip, 4.88s

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Nobody
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Post by Nobody » Tue Jun 14, 2005 7:46 am

33.x12.50 on 15x8 is perfect. It holds the bead well, and bulges enough to help protect your wheel. That's exactly what I would recommend.

The wider tire itself is going to hurt you some. 15x10's don't help. Standard backspacing is 3.5"-3.75". That's a good place keep it.

Hell I was running 36x12.50 on 15x7. Now I run them on 15x8.
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OCD4B2
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Post by OCD4B2 » Wed Jun 15, 2005 1:32 am

Well how can I adjust my backspacing? I want to know how to do it... And by the way matt, i dont go over too many rocks with my II so i don't have to worry to much :D
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Post by Nobody » Wed Jun 15, 2005 7:29 am

Backspacing is just the offset of the wheel. As mentioned, standard is typically 3.5"-3.75". Other offsets would typically be special order.

The rocks may not be a concern for you, but the curb at the mall will screw up your wheel just as easy :finger:

Even in the mud the narrower wheel will help keep gunk out of the bead

marinebroncoii
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Post by marinebroncoii » Wed Jun 15, 2005 7:49 am

You can't adjust your backspacing, it is determined by the rims you buy. When looking at rims it should say Backspacing or BS and then have a measurement. It is the meaurement from the back of the rim to the mounting surface. The backspacing determines the offset of the rims - the less backspacing the more offset the rims are, making your stance wider. If you want to change you offset all you can do is make it wider by adding wheel spacers, but they are just as hard on wheel bearings as using wheels with very little backspacing (just moves the mounting surface closer to the back of rim the distance of the thickness of the spacer.
8-9" susp, 3" body lift, 39.5x16 TRXUS STS, 342 stroker, C6, NP205, D44HD mini spool-coil sprung, D60 limited slip, 4.88s

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Post by lilBro » Wed Jun 15, 2005 8:28 am

I have a question about wheel offset and backspacing, and the application of both.

I was wondering if one couldn't use fullsize axles (9" and D44) and use wheels with less offset and alot of backspacing to move the wheels and tires back inwards, thereby reducing the amount of tire outside of the fender and possibly avoiding cutting the axles or using fender flares.

The wheels would basicly cover the brake assemblies as completely as suspension and steering gear would allow, and be closer to flat, or flush, at the front of the wheel.

I've got a feeling it wouldn't work for wheeling for various reasons like bearing wear, but would like to hear what others think about such a setup.
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Post by Nobody » Wed Jun 15, 2005 8:52 am

Yes, you can do that to some extent. Some guys do that with 8 lug axles and hummer wheels.

3 problems you'll run into are wheel/TRE clearance, tire rubbing radius arm, and your hubs sticking out in the open.

So really a 5" BS is probably the most you could get away with. That would would only save you a 1.5" on each side.

When I first did my SAS, I used 4.75BS on the front, and I hit the hubs quite a bit when out wheelin. The wheel/TRE clearance was very close.

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Post by marinebroncoii » Thu Jun 16, 2005 5:54 am

All of what Nobody said and yes it is just as hard on your bearings to go to one extreme as it is the other. it is usually you suspension and steering that limit you backspacing, if your axle has very long knuckles then when you turn the tie rod will come in contact with the edge of the rim, and like Nobody said your radius arms arm going to limit you as well. One way to get a lttle more clearance is use leafs up front with them mounted under the frame to be in as far as possible. i personally wouldn't use leafs in the front for ride quality, but i have seen some trucks with awesome flex out of leafs all around. The worst part about getting axles narrowed is getting the axles shafts cut down and resplined, other than that they aren't hard or expensive to cut down yourself.
8-9" susp, 3" body lift, 39.5x16 TRXUS STS, 342 stroker, C6, NP205, D44HD mini spool-coil sprung, D60 limited slip, 4.88s

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Post by NMB2 » Thu Jun 16, 2005 7:36 pm

i run 33x11.5's on a 15x7 rim...not sure on backspacing. they are the same rims as nobody shows in that picture....well heres a picture. the only sort of rubbing i can find so far is my tie rod on the diff cover at full lock (left) :laugh: as for axles i have a 31spline 8" in the rear and 297x D30HP up front...and lots of spare unit bearings if needed. 7.5 should have no problem with a wide tire or rim...but ive heard the Dana35 might not like it. i know NightKrawler runs some 12.5's on 15x8s and claims to never had problems.

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Post by LilBronc » Fri Jun 17, 2005 12:32 am

Stock backspacing on BII's is 4.5". Most after market rims run 3.75" It's a good compromise. I have 32x10.5's on 15x7 w/ 3.75"bs. 3" lift and minor fender mods clear w/o a problem. I recently swapped in a 35ttb and haven't had a problem with bearings or rubbing. Most manufacturers recommend rims within 1" of the treadwidth, not stated size. A 12.5 may only have 10.2" tread. And don't confuse offset with backspacing. Offset is the distance from the center of the rim width to mounting surface. Backspacing is measured from the mounting surface to rear of rim. I would personally go 8" with 3 to 4" bs.
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Post by marinebroncoii » Fri Jun 17, 2005 9:35 pm

I have heard so many different things about stock rims I don't know what to believe or tell people. Does anyone no shit know what stock rims have so I can pass the correct info. I have hear 15x6, 15x7, and 15x6.5 just for size; and have heard 3.5, 3.75, 4, and now 4.5 on backspacing. I know there are at least 7 different rims styles on RBV's but were they all different size and offset? There are the 4 spoke steel, 5 spoke alloys, smooth 4 spoke rims on rangers, the five spoke explorer alloys, the ex rims with lots of spokes, the ones like Nobody show a pic of, the plain multispoke steel rims, and probably some more I am forgetting.
8-9" susp, 3" body lift, 39.5x16 TRXUS STS, 342 stroker, C6, NP205, D44HD mini spool-coil sprung, D60 limited slip, 4.88s

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Post by OCD4B2 » Sat Jun 18, 2005 4:40 am

:D I was also checking out the steel wheels and wondered something, should I go for 3.75" or 4.5" backspacing?
230,000 miles and she still turns heads

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