Lexus IS250 2012 Tyre Size Converter - Quick Results
Tyre Size Converter - Quick Results
Using one of the standard fitment sizes listed for the 2012 Lexus IS250, we have selected 255/40R18 to get you started. If your vehicle has a different size, enter the size shown on your tyre sidewall below to compare alternatives, wheel sizes and circumference differences.
Enter your tyre size to see the closest diameter match for each available rim size. Same or larger rims, with no narrower tyres.
Closest tyre size matches
4 closest recorded alternatives for 255/40R18, within ±3% circumference. Same or larger rims; tyre width 255 mm or wider.
19-inch rim
255/35R19✓ -0.02%Same tyre widthCompare20-inch rim
255/30R20✓ -0.03%Same tyre widthCompare21-inch rim
295/25R21✓ +2.98%Width +40 mmCompareLexus IS250 tyre size conversion explained
For your IS250, changing from your selected 255/40R18 tyre on 18-inch wheels to 255/35R19 on 19-inch wheels gives a circumference decrease of 0.02%. Nominal tyre width stays the same at 255 mm. With 255/35R19, indicated speeds of 30 and 60 mph correspond to approximately 30.0 and 60.0 mph respectively, assuming the speedometer was accurate with your selected original size.
If you want to increase wheel size further on your IS250, another option to compare is 255/30R20 on 20-inch rims, up from your selected 18-inch rims. Circumference decreases by 0.03%, while nominal tyre width stays the same at 255 mm. With 255/30R20, indicated speeds of 30 and 60 mph correspond to approximately 30.0 and 60.0 mph respectively, assuming the speedometer was accurate with your selected original size.
For a larger-wheel look, 295/25R21 brings your IS250 to 21-inch rims. Measured against your selected 255/40R18, this alternative has a circumference increase of 2.98%; its nominal tyre width increases by 40 mm, from 255 to 295 mm. With 295/25R21, indicated speeds of 30 and 60 mph correspond to approximately 30.9 and 61.8 mph respectively, assuming the speedometer was accurate with your selected original size.
Choosing a wheel size increase for your Lexus IS250
Standard and original equipment sizes
Check the standard or original equipment tyre and wheel sizes approved for your exact engine and trim. A size recorded against this model may belong to another version. A genuine manufacturer wheel option still needs to match your vehicle; these calculated alternatives are close size matches, not confirmation of manufacturer approval.
Speedometer variation and effective gearing
Keeping circumference close to your original tyre limits changes to speedometer and distance readings and effective gearing. A larger circumference makes gearing taller and increases road speed at the same wheel speed; a smaller circumference makes gearing shorter. The gearbox ratios themselves do not change. The estimates above assume the speedometer was accurate with your selected original tyre; existing speedometer error and actual rolling circumference can change the result. The ±3% filter is this converter’s comparison threshold, not a manufacturer approval or a guarantee of fitment.
More wheel, less sidewall
A larger wheel paired with a lower-profile tyre can give your IS250 a sleeker, sportier appearance while keeping overall diameter close to the original. A shorter sidewall can also mean a firmer ride and less cushioning over potholes.
Tyre width, offset and full-lock clearance
Keep width increases modest and check clearance around the suspension and inner wheel arches at full steering lock and through suspension travel. Tyre width, wheel width and offset all affect whether a wheel fits without rubbing. Nominal tyre width is the section width, not the measured tread width. Choose a compatible wheel and offset for a spacer-free fit; spacers are not an automatic remedy for fouling. Confirm brake clearance, load and speed ratings and the exact vehicle application before fitting.
Results compare nominal sizes. They do not confirm vehicle or wheel fitment.