# Stop Guessing. Start Fitting. SHIROKAI's Free Wheel Fitment Calculator Is Live
You've got the widebody. Now what wheels actually fit without rubbing, spacers drama, or three trips to the shop before someone gets it right? That's exactly the problem we built this tool to solve.
The **SHIROKAI Wheel Fitment Calculator** is free, takes about 30 seconds to use, and tells you exactly what offset, backspacing, and tire sizing you're working with before you spend a dollar on wheels. [Try it here →]
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Who This Is For
Option 1: You Bought (or Are About to Buy) a widebody Kit
This one's straightforward. Our kits add serious width — 90mm per side up front, 120mm per side in the rear. That's not a suggestion, that's steel and plastic bolted to your car. You need wheels that fill that space properly, otherwise the whole build looks like it's wearing oversized pants.
The calculator has SHIROKAI fitment templates built in. Select your model year, and it spits out the target offset range, minimum backspacing, based on what actually works with our geometry. No guesswork, no forum threads from 2014 that may or may not apply to your exact build.
Option 2: Shops, Installers, and Build Guys Working Custom Projects
This is where the tool gets genuinely useful beyond just SHIROKAI customers.
You've got a client rolling in with a widened car — maybe our kit, maybe something else — and they want wheels. You need to quote fast, get specs over to a wheel vendor, and have actual numbers to back up your recommendations. Not vibes. Numbers.
The override mode in the calculator lets you punch in any fender width extension, any stock/base wheel specs and desired fitment (flush, poke, tucked), and it gives you the offset and backspacing targets to hand directly to your wheel vendor. That becomes your spec sheet for the conversation with Rotiform, Forgeline, Work, whoever you're calling.
For shops building projects under MSRP pressure — this cuts the back-and-forth. You get the data, you call the vendor with confidence, you come back to the client with a quote instead of "I'll need to look into it." That's the difference between closing the build or losing it.
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How It Works — Step by Step
Step 1: Enter your vehicle info**
Select your make, model, and year from the dropdown. If you're on a SHIROKAI kit, select the kit from the template menu and the fender width extensions auto-populate.
Step 2: Set your desired fitment style**
Choose from flush, mild poke, or aggressive poke — or enter a custom value in millimeters if you know exactly what you're after.
Step 3: Read the output**
The calculator returns:
- Target wheel offset (ET)
- Compatible rim width
BEST THING: You can play with wheel width or offset after calculations, for example it returned you 12J width, but you want to go 13J, adjust the width slider and it will change the offset automatically to keep your wheel under the desired widened arch numbers.
**Step $: Override for custom builds**
Not on a SHIROKAI kit? Running a custom flare? Hit the override toggle, enter your own fender extension measurement or stock/current wheel specs and the math updates accordingly. Same output, any input. Works for any make and model not just the SHIROKAI catalog.
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Why We Built This
Fitment questions are the number one thing our customers and dealers ask about. Every week, people ordering kits want to know "what wheels should I get?" And every week, the answer starts with the same variables — offset, backspacing, fender clearance — that you can actually calculate.
We got tired of answering the same question individually. So we made a tool that answers it better than we could in a DM, available 24/7, for free.
If you're building with SHIROKAI, this is your starting point. If you're building with anything else, this still works — the math doesn't care what brand is on your fenders.
[Open the Wheel Fitment Calculator →]
*Running a shop or building a widebody project and want to talk fitment in more detail? Hit us a message — we know what fits because we make what goes over it.
