PC Tires Tools

Plus & Minus Sizing

Moving to bigger rims, or down to steel wheels for winter? Enter your current size and get stocked sizes that keep your speedometer, ABS and gearing honest.

Current

Your current tire size

or pick it
/ R
Use the size on your door-jamb sticker, not whatever happens to be on the car now.

What Plus Sizing Is

Plus sizing means moving to a larger-diameter wheel while keeping the overall tire diameter the same. Each inch of rim you add, you take back in sidewall, and the tread usually gets about 10 mm wider. Done right, the speedometer, odometer, ABS and gearing all behave exactly as before. Done wrong, you get a wrong speedometer, rubbing and a ride that finds every pothole on Grande River Line.

Plus 1
One inch larger wheel, about 10 mm wider tread, aspect ratio drops ~10 points. The most common upgrade: sharper steering, minimal downside. Example: 205/55R16 → 225/45R17.
Plus 2
Two inches up. Noticeably firmer ride, more rim-damage risk on broken pavement, and winter tires in the new size cost more. Example: 205/55R16 → 225/40R18.
Plus 3
Show-car territory: 30–35 series sidewalls. Expect fender or liner work on many vehicles and a hard ride. Confirm load index carefully; low-profile sizes often come in lighter load ratings.
Minus 1 / Minus 2 (winter)
The reverse: a smaller steel wheel with a taller, narrower tire. Narrower tires cut through snow better, the tires are cheaper, and your alloys stay out of the salt. Example: 225/45R17 → 205/55R16 on steelies.

Before You Buy Wheels

Bolt pattern, offset, centre bore
A tire size that fits means nothing if the wheel doesn’t. The new wheels need your vehicle’s bolt pattern (e.g. 5×114.3), an offset close to factory, and a centre bore that matches or uses hub rings. We check all three when you order wheels from us.
Brake clearance
Going down a rim size for winter is limited by your brake calipers. Many vehicles with 18" factory wheels can run 17" steelies; some performance and heavy-duty packages cannot. We confirm against the vehicle before ordering.
TPMS sensors
A second set of wheels needs its own TPMS sensors or you’ll drive all winter with a warning light. We supply and program sensors and do the relearn at install.
Load index and speed rating
Every suggestion here is a geometry match only. The tire you choose still has to meet or exceed the load index and speed rating on your door-jamb placard. This is non-negotiable on trucks, SUVs and anything that tows.
Want us to spec the whole package? Text your VIN or year/make/model and the look you’re after to 519-397-4686. We’ll price wheels, tires, sensors and install together.

Frequently Asked Questions

What is plus sizing on tires?
Plus sizing is fitting a larger-diameter wheel with a lower-profile tire so that the overall tire diameter stays the same. Plus 1 is one inch up in rim size, Plus 2 is two inches, and so on. Because the overall diameter is unchanged, the speedometer, odometer and ABS keep working as designed.
What is minus sizing and why do people do it for winter?
Minus sizing is the opposite: a smaller wheel with a taller, usually narrower tire of the same overall diameter. It is the standard Ontario winter setup. Narrower tires bite through snow better, winter tires in smaller sizes cost less, and a set of steel wheels keeps your alloy rims away from road salt and curbs.
How close does the new diameter need to be?
Within 3% of the original overall diameter is the general industry rule; within 1.5% is ideal and is what this tool marks in green. Sizes outside 3% are not shown.
Why does the tool only show some sizes?
It only suggests sizes that PC Tires actually stocks online, so every suggestion is something we can ship to our Pain Court shop and install. If a size you have in mind is missing, call or text 519-397-4686 and we can usually order it.
Can I just buy the wheels and tires separately?
You can, but fitment problems almost always come from the wheel, not the tire: wrong bolt pattern, wrong offset, centre bore that doesn’t match, or calipers that hit the spokes. If you order wheels and tires together from us we check all of that against your vehicle before anything ships.
Will a bigger wheel void my warranty or affect insurance?
A plus-size within the vehicle manufacturer’s approved options generally does not. Going well beyond that, or beyond the 3% diameter rule, can affect warranty claims on suspension and drivetrain parts. Check your owner’s manual for the factory-approved wheel and tire sizes; many vehicles list two or three.

More Tire Tools

Tire Size Calculator
Compare two sizes — diameter, sidewall, speedometer error and a fit verdict.
Tread Depth Calculator
How many kilometres and months are left on your tires, and when to replace.

Calculations use the standard metric tire-size formula (sidewall = width × aspect ÷ 100; overall diameter = rim × 25.4 + 2 × sidewall). Actual mounted dimensions vary by brand, rim width, load and pressure, typically within about 1%. These tools are a starting point, not a fitment guarantee: always confirm load index, speed rating and clearance against your vehicle's door-jamb placard and owner's manual. Questions? Call or text 519-397-4686 and we'll check it for your vehicle.

Found Your Size?

Shop by size or vehicle, pick an install time at checkout, and we'll have your tires ready in Pain Court.

Shop Tires 📞 Call or Text 519-397-4686