Check whether a tire section sits inside the ETRTO rim-width range. Above max is stretch (wider rim); below min is a narrower spec — free, private, no signup.
Improves table match when provided.
Above maximum rim
The rim is wider than the approved maximum. That is stretch territory — manufacturer guidance still wins.
+16.3 mm
Rim vs section
+7.24%
Geometric %
7"
ETRTO min
8.5"
ETRTO max
Geometric stretch charts from forums are not a safety standard. Use the ETRTO range and the tire maker’s fitment list.
100% browser-based
Runs locally in this tab
No upload required
Your files never leave this device
Nothing is stored
Close the tab and the input is gone
Instant results
No queue and no server wait
Enter tire section width in millimetres, rim width in inches, and optionally aspect ratio. The checker places the rim inside, below, or above the approved ETRTO/TRA band for that section. Stretch in this tool means the rim is wider than the approved maximum — the sidewall pulled toward the lips — not a skinny tire on a too-narrow wheel.
Inside the band is the approved mounting range. Below min is a rim narrower than spec (rounder profile, not stretch). Above max is stretch territory. You also get a geometric delta in millimetres and percent between rim and section. There is no mild/aggressive score; those labels are not in ETRTO.
Aspect improves the chance of hitting the exact series row instead of a width-only fallback. A 245/30 on an 8.5" and a 245/45 on an 8.5" are not the same approval. If the table has no row, you get a clear no-table status instead of a fake stretch percentage.
No account and no upload. Widths stay in the tab. Close the page and they are gone. Stretch outside the ETRTO max can hurt bead seating and sidewall durability — this page flags the geometry, it does not certify a show-car setup as safe.
That is the 225 in 225/40R18, from 125 to 405 in 5 mm steps. Not flotation overall width in inches.
Advertised width between flanges (for example 8 or 9.5). This is the number you are testing against the approved band.
Helps select the exact ETRTO series. Leave it blank only if you know width alone.
Above max is stretch (rim too wide). Below min is a narrower-than-spec rim. Inside is the approved range. Confirm with the tire maker if you are on the edge.
Straight answers on privacy, limits, and how the workspace behaves.
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