Compare two tire sizes side by side: diameter, width, sidewall, ride height, and rev/mile, plus Preferred ±2% or Acceptable ±3% fitment bands — free online.
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Enter a stock size and a candidate — metric like 265/75R16 or flotation like 35x12.50R20 — and see overall diameter, section width, sidewall height, and the ride-height change (half the diameter delta). That is the comparison you want before a plus-size, a winter downsize, or a modest lift tire.
The workspace classifies the diameter change as Preferred (about ±2%), Acceptable (about ±3%), or Outside those bands. Those are industry rules of thumb for speedometer and clearance risk, not a law. Use them to decide whether a size is a small step or a re-gear conversation.
You get Δ diameter, width, sidewall, and rev/mile in both percent and absolute units. A wider tire can look “the same height” in a photo and still change rev/mile. Pair this page with the speedometer-error tool when indicated speed is the real worry.
No vehicle account and no upload. Paste two sidewall codes, read the diameter and rev/mile deltas, and close the tab. The sizes never go to a dealer database. Bookmark it for the parking-lot decision between two SKUs. Nothing is stored on a server.
Use the code on the sidewall or the door placard, metric or flotation. Prefixes such as P, LT, ST, or T are accepted with the size.
Type the candidate the same way. Width, aspect, and rim all affect diameter — copying the full code matters.
Each row shows percent and physical difference. Ride height is half the overall-diameter change, which is what the fender and the speedometer both feel.
Preferred / Acceptable / Outside is about diameter percent. For indicated speed at 60 mph, open Speedometer Error with the same two sizes.
Straight answers on privacy, limits, and how the workspace behaves.
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