Conical Silicone Plugs Big Size Ø 48 to 102 mm
Conical Silicone Plugs Big Size Ø 48 to 102 mm
Hitzebeständige Silikon Stopfen für die Maskierung von Bohrungen.
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Voraussichtliche Lieferung: 16. Oct - 20. Oct
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Large Tapered Silicone Plugs for Openings from 48 to 102 mm
The center bore of a wheel rim centers the wheel on the hub. If a layer of paint is present, the rim will no longer slide smoothly onto the hub lip or will bind under tension. These plugs are specifically designed for such large openings: they seal center bores, bearing seats, and pipes with inside diameters from 48 to 102 mm, withstand the heat in the curing oven, and pull out cleanly in one piece afterward. You can purchase each size individually, ideal for a set of rims or a single component.
For bores under 48 mm, seal them using our medium sizes for 20 to 53 mm. Additional styles such as caps and thread plugs can be found under plugs for powder coating.
Masking Wheel Center Bores, Wheel Bearings, and Post Tubes
Rims: Center Bore and Hub Mounting Face
On OEM rims, the center bore matches the hub centering flange exactly, approx. 57.1 mm for VW, Skoda, and Seat; 63.4 mm for Ford; or 66.6 mm for Mercedes. Aftermarket wheels often feature a larger center bore and are fitted using centering rings. This ring must also slide in smoothly post-coating. Be sure to remove plastic and aluminum centering rings prior to coating.
At least equally critical is the hub mounting face, the flat mating surface on the back of the rim where it rests against the wheel hub. Paint left between the rim and hub will yield under bolt torque, causing the connection to loosen over time. Insert the plug from the backside into the center bore and mask the surrounding mounting face with heat-resistant tape. For valve holes and lug bolt bores, use our small plugs. Matching shades for wheels can be found under our silver powder coatings.
Wheel Hubs and Bearing Seats
Rolling bearings are press-fitted into hubs or steering knuckles with interference tolerances of just a few hundredths of a millimeter. By contrast, an 80 µm powder layer reduces the seat diameter by 0.16 mm. As a result, the bearing will no longer fit, or the outer ring will deform during press-fitting, causing the bearing to run rough. Cast aluminum motorcycle wheel hubs should also be outgassed before masking. To understand why this is so important for castings, read our guide on powder coating aluminum.
If wheel studs are still present in the hub, protect their threads using silicone caps.
Posts, Railings, and Pipe Stubs
Fence and post tubes measuring 76.1 or 88.9 mm outer diameter are frequently coated prior to assembly. The plug keeps the tube end clear so post caps and connectors fit smoothly without post-processing. The same applies to engine intake and air filter stubs, where hoses must seal tightly.
Dimensions Table for Center Bores, Bearing Seats, and Tubing
You can find the center bore diameter of your aftermarket rim in its technical approval document (TÜV report). For tubing and bearing seats, measure with the internal jaws of a caliper at a minimum of two points, as large openings are rarely perfectly round. The plug fits best when your measurement falls roughly near the middle of its specified range.
| SKU | Model Number | Hole Ø | Length | Example Application |
|---|---|---|---|---|
| STO-M47-55 | M47-55 | 47.6 to 56.0 mm | 25.4 mm | Wheel center bore 54.1 mm (e.g. Toyota), bearing seat 52 mm |
| STO-M53-64 | M53-64 | 54.0 to 64.5 mm | 25.4 mm | Wheel center bore 57.1 mm (VW, Skoda, Seat) and 63.4 mm (Ford), head tube ZS56 |
| STO-M62-75 | M62-75 | 62.0 to 75.0 mm | 35.0 mm | Wheel center bore 65.1 mm (Opel), 66.6 mm (Mercedes), and 72.6 mm (many BMW) |
| STO-M68-82 | M68-82 | 68.0 to 82.0 mm | 35.0 mm | Post tube 76.1 mm (ID approx. 70 mm), wheel bearing seat 72 mm |
| STO-M76-88 | M76-88 | 76.2 to 88.9 mm | 38.1 mm | Tube 88.9 x 3.2 mm (ID 82.5 mm) |
| STO-M82-101 | M82-101 | 82.6 to 101.6 mm | 38.1 mm | Tubes 101.6 and 108 mm outer diameter, intake and air filter stubs |
Manufacturer specifications for center bores vary by model and production year. Your own measurement is always the decisive value.
Handling Large Plugs
- Account for pressure inside sealed tubes. Starting at 70 mm in diameter, trapped air becomes a critical factor: at 200 °C, expanding air exerts over 20 kg of force against a plug sealing a tube closed on both ends. Always leave at least one end or a vent hole unsealed.
- Twist in firmly. Due to the large surface area, a large plug requires more insertion force than a smaller one. Twist it in using both hands until it sits flush and even all around.
- Do not pry out. Never use a screwdriver to remove plugs. Prying will gouge the lip of the center bore or bearing seat. Pull the plug out by its protruding end with a twisting motion, using water pump pliers with plastic jaws if necessary.
- Score edges cleanly. On large diameters, a continuous coating film forms more easily over the seam. Score the powder perimeter with a utility knife before pulling the plug.
Pro Tip from Pulverkönig
I suspend rims by a lug bolt hole rather than the center bore. This leaves the center bore clear for the plug while ensuring the hook maintains direct metal-to-metal grounding contact. I inspect the seating face on that single bolt hole after curing and clean it to bare metal if needed.
Specifications and Delivery Units
- 6 sizes covering inside diameters from 47.6 to 101.6 mm
- Lengths of 25.4 mm, 35 mm, or 38.1 mm, increasing with plug size
- Solid silicone rubber construction, heat resistant up to 315 °C
- Recommended by the manufacturer for e-coating (KTL), liquid paint, anodizing, and electroplating processes
- Available individually or at discounted rates in packs of 3 and 5
- Reusable for many curing cycles with careful handling
Frequently Asked Questions About Large Silicone Plugs
How many sizes do I need for passenger car rims?
Most passenger car center bores range between 54 and 73 mm. The three sizes M47-55, M53-64, and M62-75 cover virtually all standard vehicles.
Must the centering ring be removed before coating?
Yes. Plastic rings will melt in the oven, while aluminum rings will acquire a coating layer and no longer fit afterward. Insert the plug directly into the rim's center bore.
How should I store plugs between uses?
Store them flat, clean, and without weight resting on them. Stacking large plugs under heavy loads can permanently deform them, preventing them from forming a uniform seal.