Free tool
Will these wheels fit?
Pick your car, type in the numbers off the ad, and get an answer in words before numbers. Built for drift fitment: poke at the guard, backspacing at the coilover, what stretch buys you, and whether it is still street legal in Australia.
Compared with 18x9.5J ET+27 on a guard that sits about flush with the guard.
The wheels you are looking at
Needs a guard roll
It sits 12mm further out than what you run now. Roll the guard lip flat and it should clear. No cutting.
Before anything else: a S13 / 180SX is 4x114.3. If the ad does not say that, none of the rest matters.
Top half of the wheel, cut through the centre, outboard on the left. Every width, lip and gap is real millimetres at one shared scale. The height of the guard and the coilover glyph are illustrative, not your exact car.
Poke change
+12mm
Outer lip moves toward the guard.
Inner clearance
+12mm
Clearance gained at the coilover.
Overall width
0mm
Backspacing 148mm to the flange.
Tyre diameter
0mm
245/35R18 is a mild stretch on a 9.5J.
What it takes
- Two to three degrees of negative camber tilts the top of the tyre inboard and is the cheapest guard clearance you will ever buy.
Street legal in Australia
This widens your track by 12mm a side, 24mm across the axle. VSB14 Section LS allows a passenger car track increase of 25mm in total. The tyre must also sit inside the guard with the wheels straight ahead, and spacers are not permitted unless they were fitted as original equipment.
General information, not advice. State requirements and engineering pathways differ, and a track-only car is a different conversation.
Verdicts are bands, not promises. Ride height, camber and tyre choice move every one of them, which is why the fitment chart this tool is calibrated against publishes ranges rather than single numbers. Test fit before you mount fresh tyres.
How offset actually works
Offset (ET) is the distance in millimetres from the wheel's mounting face to its centreline. Lower or negative offset pushes the whole wheel outboard: more poke, more guard risk, more front-on presence. Higher offset tucks the wheel inboard, eating the gap to your coilover instead. Width changes split the difference. Go two inches wider at the same offset and one inch lands on each side, which is why width and offset only ever mean anything together.
One trap worth knowing before you compare listings. Rim width in J is measured across the bead seats, not lip to lip, and there is a flange of about 12.7mm either side on top of it. So backspacing quoted to the bead seat and backspacing quoted to the flange differ by roughly 12mm, which at drift tolerances is the difference between fitting and not. This calculator measures to the flange throughout, because the flange is the metal that actually hits things. Ask a seller which way they measured before you send a deposit.
For drift setups the inner number usually bites first. Steering angle sweeps the inner barrel through the space beside the strut, so a wheel that clears when parked can still saw through a coilover sleeve at full lock. That is why angle-kitted fronts generally want a higher offset than the same width on stock steering, not a lower one. If there is angle hardware in the picture, read the angle kit wheel clearance guide and protect the backspacing number harder than the poke number.
The tyre matters as much as the rim. A tyre narrower than its design rim pulls the sidewall inboard until the rim lip becomes the widest point of the whole assembly, which is exactly why stretch buys guard clearance. A tyre on or above its design rim bulges past the lip and hits the guard before the wheel ever gets there. The drawing shows this: watch the sidewall change shape as you change tyre size.
The verdicts this tool gives are bands, not promises, and they are calibrated against the S-chassis wheel fitment chart, which publishes ranges because ride height, camber and tyre choice genuinely move every one of them. Two identical cars at the same wheel spec can land on different answers. Use this to narrow your shopping, then test fit on your own car at your own ride height before you mount fresh tyres.