Tire essentials
What happens when you increase tire width?
Adding width changes more than the number at the start of the size. If the aspect ratio stays the same, diameter grows too.
Width also changes sidewall height
205/55 R16 and 215/55 R16 differ by 10 mm in nominal width. Their sidewalls are 112.75 mm and 118.25 mm, respectively. That makes the wider size 11 mm taller overall, despite using the same wheel diameter. At an indicated 100 km/h the larger diameter produces a theoretical 101.74 km/h road speed.
Do not equate width with a fixed grip gain
Contact-patch shape changes with width, but load and inflation pressure influence its area. Compound, tread design, temperature and road conditions affect grip. A wider tire can also change steering feel and may alter rolling resistance; size alone cannot quantify those outcomes.
Check space on both sides
Check the tire maker’s permitted rim-width range and its actual section width on the intended wheel. Then check suspension and body clearance throughout steering and suspension travel. Static clearance in a parked car is not the whole fitment question. Offset changes can move additional width inward, outward or both.
Method and references
Examples use nominal geometry and fixed-price scenarios, with no vehicle-specific specifications implied. See our calculation methodology and editorial policy.
Dimension reference: Tire Rack: calculating tire dimensions. Consult the tire and vehicle manufacturers for actual fitment requirements.