4 Wheel & Off Road - - CONTENTS - Verne Si­mons BY EDI­[email protected] PHO­TOG­RA­PHY TRENT MCGEE AND VERNE SI­MONS

Do you know about backspacing? Safety beads? Cen­ter bore?

WDo you know about wheel backspacing? Safety beads? Cen­ter bore? Don’t worry, we’re here to help and teach. At the end of the day all your ques­tions about which parts make a wheel should be an­swered, and if we don’t an­swer a ques­tion, don’t worry; it’s prob­a­bly not that im­por­tant.


Wheel di­am­e­ter is one of the most ba­sic di­men­sions you need to know when think­ing about wheels (and tires). In the off-road world wheel di­am­e­ter is gen­er­ally tied to brake size, and by that we mean which wheels will clear your ve­hi­cle’s brakes, above all else. For cars, larg­er­diam­e­ter wheels also make han­dling crisper be­cause with the same out­side di­am­e­ter tire there is less side­wall to flex with weight changes and side loads ap­plied to the wheel/tire in a turn.

When off-road, larger wheels tend to create more prob­lems than they solve. Of­froad ve­hi­cles with large-di­am­e­ter wheels are more prone to tire side­wall dam­age, wheel rim dam­age, and tires slip­ping off a bead when aired down. We pre­fer 15- to 17-inch wheels for a num­ber of rea­sons un­less you’re run­ning a re­ally large tire. A good rule of thumb is to run the small­est di­am­e­ter wheel that will clear your brakes.


Also one of the most ba­sic wheel di­men­sions is width. There are two schools of thought in the off-road world when it comes to wheel width. Both have their mer­its—and de­trac­tions.

The “wider is bet­ter” crew says that wider wheels add track width and thus sta­bil­ity. Wider wheels gen­er­ally al­low a tire to be as wide as possible, aid­ing in flota­tion in soft sand or mud. Fans of wide wheels also re­port that wider wheels al­low a tire to be less sus­cep­ti­ble to fall­ing into a rut or go­ing off­line on rocks.

The “nar­rower is bet­ter” crowd be­lieves, among other things, that the tire is less likely to slip off the bead when aired down and wheel rim dam­age is less likely (be­cause the tire’s bulge helps pro­tect it).

Who’s right? The truth is it boils down to your in­tended use, style of driv­ing, and ex­pe­ri­ences. Our per­sonal pref­er­ence is to run as nar­row a wheel as rec­om­mended for a given tire width, but hon­estly it’s noth­ing more than our pref­er­ence. Both wide and nar­row wheels have ben­e­fits and draw­backs and yield a dif­fer­ent look to the tire and ve­hi­cle.


Bolt pat­tern is sim­ply the di­am­e­ter and num­ber of wheel studs on your axles. This gen­er­ally varies by year, make, and model. Com­mon pat­terns are 5-on-41⁄2, 5-on-5, 5-on 51⁄2, 6-on-51⁄2, and 8-on-61⁄2. The first num­ber tells how many lug holes, and the sec­ond num­ber is the di­am­e­ter of the cir­cle. For ex­am­ple, a 5-on-51⁄2 bolt pat­tern means there are five lug holes around a 51⁄2-inch­di­am­e­ter cir­cle. A rule of thumb is that larger and more wheel stud open­ings are stronger, but bolt pat­tern is gen­er­ally dic­tated by what axles you are run­ning (and that’s usu­ally dic­tated by tire size, in­tended use, weight, and horse­power/torque).


Wheel off­set and backspacing are prob­a­bly two of the more con­fus­ing wheel terms you’ll ever run into. They are con­fus­ing be­cause they are two dif­fer­ent meth­ods of de­scrib­ing the lo­ca­tion of the wheel mount­ing sur­face rel­a­tive to the front and back of the wheel (front be­ing to­ward the curb, and back be­ing to­ward the dif­fer­en­tial).

Backspacing is sim­ply the mea­sure­ment from the wheel mount­ing sur­face to the rear edge (rim) of the wheel.

Off­set is ei­ther a positive value, a neu­tral value (zero), or a neg­a­tive value. What it de­scribes is the dis­tance of the wheel mount­ing sur­face from the cen­ter­line of the wheel. A wheel with zero off­set means the wheel mount­ing sur­face is di­rectly at the mid­dle of the wheel. A positive num­ber means the wheel mount­ing sur­face is closer to the front of the wheel (curb side). A neg­a­tive off­set means the wheel mount­ing sur­face is closer to the back of the wheel (dif­fer­en­tial side).

A wheel with shal­low backspacing has neg­a­tive off­set. This makes the track width of the ve­hi­cle greater and may pro­vide more clear­ance for shocks and other axle com­po­nents, but can be harder on steer­ing parts. A wheel with deep backspacing and positive off­set makes a ve­hi­cle nar­rower and is gen­er­ally eas­ier to steer, but the wheel can in­ter­fere with sus­pen­sion parts. Once again, nei­ther ex­treme is nec­es­sar­ily good for your 4x4. Our per­sonal pref­er­ence if given a choice is to run a wider axle with a wheel with deeper backspacing (positive off­set).


The safety bead (ar­row) on these wheels is large and abrupt, and that ‘ what you want in a 4x4 wheel. That will help keep the tire seated on the bead when you’re run­ning low pres­sure. Low tire pres­sure in­creases the foot­print of your tire, giv­ing you vastly bet­ter trac­tion on rocks, sand, snow, and other of­froad sur­faces.


Older wheels, which are al­most cer­tainly go­ing to be steel, may be in­tended for use with in­ner tubes. They may lack safety beads al­to­gether. Here’s a trick: You can tell from the out­side of a steel wheel whether or not it has a safety bead, even if it has a tire mounted on it. Just look for this in­dent (ar­row) about an inch in­side of the wheel rim.


The rim, or lip, of a wheel is one of the most vul­ner­a­ble parts of a wheel. It is the first part to come into con­tact with rocks on the trail. For that rea­son we like to run a wheel with a thick durable rim. These Dick Cepek wheels have seen heavy use on rock trails. The thick cast alu­minum lip may be scarred and ugly, but it’s not dam­aged.


Beadlock wheels are de­signed to be abused, so it’s good to see the very strong in­ner rim, or lip, on these Method Beadlock Wheels we got from Summit Rac­ing Equip­ment. Don’t over­look the in­ner rim of a wheel just be­cause you don’t re­ally ever see it. These will see rocks and will stand up.


Here are two older steel wheels that help us show you about a wheel’s cen­ter bore. Both wheels are 15 inches in di­am­e­ter, both have a 5-on-51⁄2 bolt pat­tern, but the wagon wheel on the left has a large wheel cen­ter bore. That means it will clear the lock­ing hub on an old Jeep. The wheel on the right is an old Ford


The safety bead, or bead seat, is a raised lip about an inch in­side the wheel’s outer edge or rim where the tire sits. The safety bead, in con­junc­tion with air pres­sure, helps pre­vent the bead of the tire from slip­ping in­ward. If the tire’s bead does slip over the safety bead then all the air will es­cape from the tire/wheel. If you’re lucky all you have is a flat. If you’re un­lucky you have just de­stroyed your wheel or rolled your 4x4 when the wheel dug into the ground.

One would expect all safety beads to be about the same size and shape, but they are not. Some are larger than oth­ers, and some wheels have al­most no safety bead to speak of. The worst of­fend­ers are go­ing to be wheels de­signed to be used with in­ner tubes and, for some rea­son, 16.5inch di­am­e­ter wheels, which seem to lack a de­cent safety bead.


This is the edge of the wheel ei­ther on the front face (curb side) or the back face (dif­fer­en­tial side) of the wheel. The rim is fac­tory wheel for a 2WD car. The bolt pat­tern is right for an old Jeep, IH, Bronco, Suzuki Samu­rai, and more, but the small­ish cen­ter bore is a problem for fit­ment.


You can tell this wheel is lug-cen­tric and not hub-cen­tric be­cause of the gap be­tween the wheel’s cen­ter bore and the hub.

im­por­tant be­cause it, along with air pres­sure and the wheel’s safety bead, holds the tire on the wheel. The wheel rim can be bent or dented off-road, and that’s bad. Gen­er­ally we look for steel wheels be­cause they can be bent back into shape, or alu­minum wheels with a thick outer rim. That al­lows you to beat them against rocks, logs, and other trail de­bris with­out too much worry.


The hole in the cen­ter of the wheel is called the cen­ter bore. Gn­er­ally the size and prop­er­ties of the cen­ter bore are de­ter­mined by the bolt pat­tern and how the wheel mounts to the hub. Mostly what you will want to know is whether or not the cen­ter bore of the wheels you’d like to run will clear your hubs, lock­ing If there is no gap, you may have wheels that are hub-cen­tric. That doesn’t mean you cannot use lug-cen­tric wheels, but to be safe you’d bet­ter in­ves­ti­gate the sit­u­a­tion a bit more. Lug­cen­tric wheels are re­tained by con­i­cal lug nuts, while hub-cen­tric wheels will have a lug nut with a straight shoul­der and/or a washer un­der a flat base (with no ta­per).

hubs, and or wheel flanges.

Many fac­tory wheels are hub-cen­tric, mean­ing the wheel in­dexes on the axle flange or part of the hub. These wheels trans­mit forces from the tire and wheel to the hub di­rectly and via the lug nuts/ wheel studs.

Most af­ter­mar­ket wheels are lug­cen­tric, mean­ing the wheel is cen­tered on the hub us­ing the lug nuts alone. This can cause dam­age to the lug nuts and fail­ure when the wheels and tires take heavy hits. Most af­ter­mar­ket wheel in­stall­ers will know whether your 4x4 is an od­dity and cannot run lug-cen­tric wheels. We have used and abused lug-cen­tric wheels for decades with­out any failures, but if it con­cerns you, know what you need and why. Also, many lug-cen­tric wheels can be made hub-cen­tric with adapter rings.

2 2 With a straight­edge and a tape mea­sure you can mea­sure backspacing on any wheel. It’s a bit harder if there’s a tire on the wheel, but we bet you can fig­ure it out. Off­set is a sim­i­lar mea­sure­ment, specif­i­cally the dis­tance of the wheel mount­ing...

3 3 Wheel width is mea­sured be­tween the in­sides of the outer rim, or lip, of the wheel. This Pro Comp Va­por Pro 2 Com­pe­ti­tion Beadlock is 17x9; that is, 17 inches in di­am­e­ter (at the bead) and 9 inches be­tween the outer rims. If you want to imag­ine...

1 1 A wheel’s out­side di­am­e­ter plays a role in many as­pects of how a wheel works with a tire. We pre­fer 15-inch (al­though they are get­ting harder to find and are old school), 16-inch, 17-inch, and oc­ca­sion­ally all the way up to 20-inch if we’re...

4 Wheels with deep backspacing (or positive off­set) like those found on mil­i­tary Humvees make big tires a bit eas­ier to steer and are eas­ier on ball joints, tie-rod ends, and more. But they also nar­row the track width of the ve­hi­cle, and the wheel can...







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