SMG SPEED SHOP / FITMENT LAB
Your SMG guide to wheels, tires, and brake clearance. Understand the measurements, compare complete setups, and build your wheel order with our team.
01 / YOUR CAR, YOUR BUILD
Two rear tires need enough room between their centers. For a matching pair with the same published half dual spacing (HDS), center-to-center spacing is twice HDS. Use the wheel maker’s HDS or outset for the rear mounting faces, not the front inset or a generic offset.
Enter the exact specifications and confirm the matching rear pair to compare spacing.
This compares the numbers you enter. It does not measure the tire-to-tire gap or approve the assembly. Confirm wheel and tire ratings, loaded tire clearance, inflation, hub and stud engagement, and brake clearance with SMG. Mixed wheel designs or changed mounting faces need a separate review. The rear comparison tab represents one wheel position; check the complete rear pair separately.
Review the exact wheel and tire pair with SMG →SMG’s wheel specifications load by exact SKU when available.
YOUR SMG CATALOG
These are catalog candidates, not a brake-clearance certification. Open the product for application notes and verify the exact SKU before ordering.
SMG WHEEL SPECIFICATION LIBRARY
Look up exact wheel specifications in SMG’s technical library, including wheels outside the vehicle selector. These are wheel specifications, not vehicle applications. Bolt pattern, offset and diameter alone do not establish brake, tire or body clearance.
37,142 exact SKU records · technical snapshot October 27, 2026.
| Exact SKU / brand | Size / position | Bolt pattern / bore | Offset / backspacing | Load / barrel | Catalog lookup |
|---|
Barrel codes are supplier codes, not measured spoke or caliper clearance. Blank/drill-to-order wheels require final drilling and machining confirmation. Verify exact load suitability, tire ratings, hardware and wheel application with SMG. Catalog lookup does not establish that SMG stocks or sells a matching SKU.
SMG DOMESTIC FITMENT GUIDE
Find GM, Ford, and Dodge wheel applications compiled and reviewed by SMG, including options beyond the vehicle selector. Keep the exact brake package, pad, axle position, and footnotes with every part number.
137 application groups · 1973 configurations · application part numbers. Reviewed October 21, 2026.
| Wheel / axle | Pad / offset / BS | Exact wheel part numbers | Compare |
|---|
Fitment requirements vary by wheel design and vehicle. Broad generation/body references require an exact model-year, trim and brake review with SMG. Read every marked installation requirement before choosing a wheel. Some listings are historical or have unresolved specifications. Ask SMG to confirm the current SKU and application before ordering. Comparison buttons load dimensions only.
SMG DRAG WHEEL GUIDE
Choose your car above to see its supported wheel sizes, axle positions and installation requirements. Front and rear brake clearance are separate checks.
Supported SS and ZL1 applications include conditional 15×10 rear WELD and Forgestar options. Earlier Camaro generations also have listed front and rear 15-inch applications. Your year, trim, hubs and installed brakes determine which entries appear.
Modern rear-only listings require the specified conversion. A rear conversion does not establish 15-inch front clearance, and different kits are not automatically interchangeable.
Find Camaro drag wheel options →Explore listed WELD and Race Star Fox-body, SN95 and S197 applications, plus conditional S550 options. Match the actual four- or five-lug hubs and the exact brake package.
Some combinations require a small brake kit, sway-bar relocation, suspension clearance work or other listed hardware. Select your Mustang to review the exact wheel and axle requirements.
Find Mustang drag wheel options →The guide includes conditional WELD rear 15×10 entries for the CTS-V3. Match the exact third-generation rear conversion, wheel, brake and suspension hardware with SMG.
A rear conversion does not establish front-wheel clearance. Keep the required front/rear tire-height relationship and verify the complete package before ordering.
Find CTS-V3 drag wheel options →SMG APPLICATIONS / EXACT REQUIREMENTS
Choose the exact vehicle application below. These application records are available alongside the catalog vehicle selector. They apply to the named wheel designs; dimensions alone do not prove another wheel clears the same brakes.
SMG application review · October 21, 2026. Keep every fitment requirement with your wheel choice.
REAL BUILDS / DOCUMENTED CONDITIONS
Real-world build reports help explain the details. These reported examples illustrate the details that affect fitment; they are not a fitment guarantee for another car.
Rohana RFX11: front 20×10 +25, rear 20×11 +35. Michelin Pilot Sport 4 S: 275/35R20 front, 305/35R20 rear.
Reported stock suspension, no spacers, no modifications, and no rubbing. Brake package and measured clearances are not established by this record.
Shop matching wheels at SMG →Ferrada FR3: front 20×10 +13, rear 20×10.5 +20. Continental Extreme Contact: 285/35R20 front, 315/35R20 rear.
Reported stock suspension, no spacers or modifications, and no rubbing. The gallery describes visible poke. Exact caliper-to-spoke clearances were not provided.
Shop matching wheels at SMG →Vertini RF1.2: front 20×9 +15 with 245/40R20; rear 20×12 +27 with 315/35R20.
The listing reports stock ride height, rubbing, and rear inner-wheel-well trimming. This is a modification example, not a direct-fit recommendation.
Shop matching wheels at SMG →MOMO Anzio: front 19×9.5 +22 with 255/35R19; rear 19×10 +40 with 285/30R19 Hankook Ventus V12 Evo 2 tires.
The owner reports stock suspension, no spacers, no trimming and no rubbing. Exact brake clearance, wheel part numbers, hardware and load suitability are unverified. This example does not resolve the OE rear-wheel specification conflict.
Review wheels with SMG →Example geometry does not replace checking the exact wheel SKU, brakes, and your vehicle. SMG can help confirm the details for your vehicle.
02 / SEE WHAT CHANGES
Compare one axle at a time. Use the front / rear switch to keep two independent setups.
Width is measured between the tire’s bead seats. The wheel’s outer lips add extra width.
A spacer moves the wheel outward. Effective offset = wheel offset minus spacer thickness.
KEEP THE WHEEL AND TIRE TOGETHER
The tire calculator opens with this axle’s current/proposed sizes and both proposed axle sizes when provided. Labeled tire dimensions are estimates; approved wheel-width range and mounted dimensions come from the exact tire maker.
PLUS / MINUS SIZING
Plus sizing uses a larger wheel with a shorter sidewall; minus sizing uses a smaller wheel with a taller sidewall. Wider wheels and tires also change clearance. Start with this axle’s current tire above, then enter the target dimensions.
Calculated sizes can be checked against SMG’s tire technical snapshot. Source records do not establish stock or vehicle approval.
| Calculated tire size | Diameter / difference | Sidewall / at an indicated 60 mph | Use for comparison | Source-listed tire specifications |
|---|
Tire snapshot: October 21, 2026. Source-listed actual diameter is not loaded rolling circumference. A source wheel-width range is not vehicle approval; confirm it for the exact tire model with SMG. The percentage is your comparison limit, not a vehicle approval. Check the exact tire’s approved wheel-width range, load and speed rating, mounted dimensions, body clearance, and brake clearance. Preserve the vehicle maker’s required front/rear rolling ratio for AWD, ABS, and stability control; matching each axle separately does not prove that ratio.
Compare selected pair in tire calculator →WHEEL CROSS-SECTION
Scaled bead-seat envelope, viewed from above; tires and flange shape omitted. Left = suspension. Right = fender. Red line = hub mounting plane.
BACKSPACE / OFFSET CONVERTER
The common +1 inch allowance is an estimate for both flanges combined. Measure actual overall width for an exact conversion. Backspacing is measured to the rear outer flange; offset is referenced to the bead-seat centerline.
CLEARANCE BUDGET
Use comparable wheel bead-seat reference points. Static wheel room does not account for tire bulge, steering, suspension travel, alignment changes, or dynamic flex. Zero or negative room is a conflict.
03 / THE PART MOST PEOPLE MISS
The right diameter and offset are only part of the answer.
Radial clearance: space above the caliper, inside the wheel barrel. Think of fitting a big brake inside a hoop.
Axial clearance: space between the outer face of the caliper and the backs of the spokes. Think of closing a lid over something tall.
Two 18×10 +35 wheels can have completely different spoke and barrel shapes. One may clear your brakes while the other contacts them.
X-FACTOR / SPOKE CLEARANCE / PAD HEIGHT
“X-factor” often describes room behind the spokes for a brake caliper. It is not a universal rating you can reliably compare across brands. Ask which reference plane and radial location a measurement uses.
WELD’s low, medium, and high pad options describe wheel configurations used for different applications. The exact part number and application guide matter; “high pad” alone is not proof that every big brake fits.
Concavity and lip depth describe appearance. They do not tell you how much room exists behind a spoke.
Shop matching wheels at SMG →MEASURED GAP CHECK
No universal minimum is assumed. Use the wheel/brake maker’s required clearances and an actual-size template for the exact kit. Check the complete profile through a full wheel rotation, including balance weights.
SMG BRAKE-ENVELOPE LIBRARY
Look up a Method wheel SKU for published spoke-depth and barrel measurements. These describe the wheel’s shape, not the remaining gap around your caliper.
October 15, 2026 technical snapshot. Compare the complete brake envelope using the same mounting-face plane and radial positions. A few measurement points cannot establish clearance through a full rotation. A value of 3 mm may be a source default; SMG must confirm it. No missing measurement is treated as zero.
04 / SPEAK WHEEL FLUENTLY
Start with this example: 18×10 · 5×120 · ET +35 · 6.88" BS · 72.6 mm bore. It describes a wheel; it does not name a vehicle it fits.
No matching terms. Try a shorter word.
SMG WHEEL FITMENT SUPPORT
Find wheel options in our catalog, compare your setup, and let SMG check the exact wheel, brake package, hardware, and tire combination before you order.
Shop wheels for my vehicle →LET’S GET THE DETAILS RIGHT
Send the vehicle, brakes, suspension, wheel SKU, and your comparison together.
Calculated dimensions describe geometry. Final fitment also depends on exact wheel and tire construction, brakes, load capacity, hardware, steering, suspension movement, alignment, and vehicle modifications. Have SMG confirm the application before ordering, and follow the wheel and brake installation requirements.
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