How to Choose Implement Wheels, Hubs, and Spindles

Choosing implement wheels, hubs and spindles starts with two matches: the wheel must fit the hub, and the hub must fit the spindle. A matching lug count alone does not establish either one. For farm equipment, record the complete bolt pattern, wheel size, center opening and hub identification before ordering.

Southwest Wheel's catalog includes 27 implement wheel listings, 12 hubs with parts, 12 hub-with-spindle packages and 12 standalone agricultural spindles. Start with Implement Wheels and Hubs, then narrow the choice by the equipment's requirements rather than appearance.

Key takeaway

• Read both numbers in a bolt pattern. Six lugs on a 6 in. circle is not interchangeable with another six-lug pattern.
• Match wheel size and center opening separately. Diameter and width do not identify the hub pilot or wheel offset.
• Choose a spindle by its named hub application. Several hubs share a bolt pattern without sharing a spindle.
• Use only the selected product's rating. A part-number prefix, lug count or similar-looking item does not establish capacity.

How the wheel, hub and spindle work together

The wheel carries the tire and attaches to the hub. The hub rotates on bearings around the spindle. The spindle supports that rotating assembly and connects it to the implement's structure. Each connection has its own fit requirements; choosing one component does not automatically identify the other two.

For an existing implement, identify the current hub and record the wheel markings before disassembly. For a new wheel end, work from the equipment's required load, tire size, mounting arrangement and clearances. A hub-with-spindle package can simplify selecting those two components together, but it does not establish compatibility with every wheel or equipment frame.

Step 1: Read the complete implement bolt pattern

The first number is the number of mounting holes. The second is the diameter of the circle passing through their centers. For example, 6 on 6 in. means six mounting holes on a 6 in. bolt circle. Listings may shorten that to 6-6. Likewise, 5-5.5 means five holes on a 5-1/2 in. circle, not a 5 in. circle.

6 on 6 in. is an implement-wheel pattern, not a trailer-wheel pattern. Do not substitute a trailer wheel because it also has six lugs. Count the holes and verify the bolt-circle diameter from the exact listing or a suitable bolt-pattern gauge. For an odd-numbered pattern, do not treat an arbitrary hole-to-hole measurement as the bolt-circle diameter.

The pilot dimensions above come from the corresponding implement hub listing titles. They are not a universal fit chart for every wheel with that lug count. Confirm the selected wheel's center bore is compatible with the hub pilot, along with the mounting hardware and seating requirements.

Step 2: Match wheel diameter, width and center bore

Read wheel size as diameter x width. A 15 in. x 6 in. wheel is a different size from a 15 in. x 8 in. wheel even when both have a 6 on 6 in. pattern. Use the tire's approved rim requirements and the implement's specifications to choose the size; do not select by bolt pattern alone.

For example, part 106533 is listed as a 15 in. x 6 in. implement wheel with a 6 on 6 in. pattern. Its own product summary specifies a 4-5/8 in. center bore. Part 107174 is a 15 in. x 8 in. implement wheel with an 8 on 8 in. pattern and a 6 in. center bore. These are separate checks, not interchangeable wheel choices.

Also verify offset, clearance and compatible wheel hardware on the exact wheel being ordered. Do not borrow offset, center-bore dimensions or capacity from a nearby listing, a related-product card or another wheel of the same diameter. Browse Ag Wheels after recording the full size and pattern.

Step 3: Match the hub to the spindle by hub number

The agricultural spindle titles identify the implement hub they fit. Use that complete hub number, including its suffix, rather than choosing a spindle from the wheel's bolt pattern. A six-lug wheel does not tell you which six-bolt hub or spindle is on the equipment.

For example, spindle SP-124163NWC-100 is listed for hub AG-H1244500-1ZHA. Spindle SP-803213NWC-155A is listed for hub AG-H8036600-1ZHA. Other standalone listings name AG-H6116600-1ZHA or AG-H8886600-2ZHA. Those last three hubs all have 6 on 6 in. wheel patterns in the catalog, but the spindle listings identify different matching hub numbers.

If replacing only the spindle, start with the hub identification and confirm the spindle's own dimensions and mounting requirements against the equipment. If the hub identification is missing, do not guess from its appearance. Record bearing and seal identification and the relevant dimensions for further comparison before ordering.

Step 4: Choose a hub with parts or a hub with spindle and parts

In this implement line, the hub-with-spindle listings use the WS suffix. Compare AG-H8036600-1ZHA with AG-H8036600-1ZHAWS the same way: the listing title distinguishes the hub-with-parts option from the hub-with-spindle package. Read the actual contents rather than treating every package as a complete wheel, tire or equipment assembly.

A matched hub and spindle still need the correct wheel, tire, hardware and equipment attachment. Have a qualified installer review mounting and installation requirements. Southwest Wheel sells new product; it does not provide installation, welding, alignment or repair service.

Step 5: Verify capacity without decoding the part number

Use a capacity only when it appears in the selected product's own title or primary specifications. Do not decode H124, H356 or another part-number segment as a load rating, and do not transfer a related item's rating onto the product being selected.

The TruRyde AG-H608B8800-2ZHAWS listing explicitly states 6,000 lb. for its 8 on 8 in. implement hub with spindle and parts, with a 6 in. pilot. That statement applies to that listing; it does not establish the capacity of every 8 on 8 in. hub, wheel or spindle.

Check the wheel, tire, hub, spindle and implement requirements together. A rating on one component does not increase the rating of the rest of the equipment. If the selected part's rating or intended application is not established, confirm it before ordering rather than estimating from size or lug count.

Final checks before ordering

• Wheel diameter and width, plus the tire's approved rim requirements.
• Complete bolt pattern: hole count and bolt-circle diameter.
• Wheel center bore and compatible hub pilot.
• Wheel offset, equipment clearance and compatible mounting hardware.
• Complete hub number and the spindle listing that names it.
• Bearings, seals, spindle dimensions and equipment mounting requirements.
• Hub-with-parts versus hub-with-spindle package, actual contents and required quantity.
• Documented component ratings and the equipment's intended farm or implement application.

FAQ

Will any six-lug wheel fit a six-bolt implement hub?

No. The bolt-circle diameter must match, and the wheel center bore, hardware, size and clearance still need checking. A 6 on 6 in. implement pattern is not a generic six-lug trailer-wheel fit.

Can I buy a spindle using only the hub's bolt pattern?

No. Several implement hubs share a bolt pattern. Use the agricultural spindle title's named hub application, then verify the equipment mounting details.

Does a hub-with-spindle kit include the wheel and tire?

Do not assume it does. The title identifies a hub with spindle and parts. Check the selected package's contents and choose the matching wheel and tire separately when they are not included.

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