Plus-size a truck wheel without changing diameter.

How does this Tacoma plus size calculator work?

Plus sizing means moving to a bigger wheel and a shorter sidewall so the tire stays the same overall height. The calculator works backward from your current tire's diameter: give it a new rim size and a section width, and it finds the aspect ratio that keeps a Tacoma or any other midsize pickup at the same height, snaps it to a ratio tires are actually made in, and tells you how close the result lands.

What do I enter?

• Your current tire size, metric or flotation.
• The new rim diameter: 16, 17, 18, 20 in.
• The new section width in millimeters, pre-filled with your current tire's width so you can see a like-for-like swap first.

What does it show?

• The suggested metric size for the new wheel.
• The exact aspect ratio before rounding and the rounded, manufactured aspect ratio.
• Resulting vs target diameter and the percent difference, with a badge when the result lands within ±3%.

What size keeps 265/70R17 the same height on 18 in wheels?

Start from the 2026 TRD Off-Road's factory 265/70R17, 31.61 in tall. On an 18 in wheel the sidewall has to be (31.61 − 18) ÷ 2 = 6.80 in. At the same 265 mm width that is an aspect ratio of 65.2, which rounds to 65: 265/65R18, 31.56 in tall, -0.14% from the original.

That is the same 265/65R18 the 2026 TRD Sport runs on its factory 18 in wheels in Taco Tires' fitment data. The table runs the same math for 265/70R17 and 285/70R17 on every rim the calculator offers.

What are the plus and minus size equivalents for 265/70R17 and 285/70R17?

Each cell holds the section width constant (265 mm and 285 mm) and solves the aspect ratio for that wheel, exactly as the calculator does with its default width. A narrower or wider tire changes the answer, so enter the width you plan to buy.

• Aspect ratios snap to 5-point steps, so a result can land a little under or over the starting diameter. Within ±3% keeps the speedometer and gearing close to where they were.
• A solved size is a size code, not a guarantee someone sells it in the tread you want, so check availability. Low-profile sizes also carry less sidewall for airing down and pothole protection.
• A new wheel also brings a new offset and width, which change clearance more than the plus size itself; see the wheel offset calculator.

How is it different from a generic calculator?

• Starts from real Tacoma sizes: the defaults are the 4th gen TRD Off-Road's factory 265/70R17, and the equivalents land on sizes Taco Tires has pages for, such as 265/65R18, with the trims that run them.
• Only sizes that exist: the aspect ratio is rounded to a manufactured step and the result is re-parsed, so you never get a 65.2-series tire that cannot be bought.
• Shows the error instead of hiding it: the exact aspect, the rounded aspect, and the diameter gap are all on screen, so you can see why one width works better than another.

Can I put 18 inch wheels on a truck that came with 17s?

Usually, if the tire keeps the same overall height and the wheel clears the brakes and suspension. On a midsize pickup like the Tacoma, 265/70R17 becomes 265/65R18 on an 18 in wheel at -0.14% diameter change, so the speedometer and gearing stay put. The trade is a shorter sidewall: a firmer ride and less cushion off-road. Check the new wheel's bolt pattern, center bore, and offset for your generation before you buy.

Related: 265/70R17 on a Tacoma · 265/65R18 on a Tacoma · 285/70R17 on a Tacoma · Wheel offset calculator.