Best For
- Sporty handling and a wider contact patch on performance-oriented cars
- Drivers who want sharper steering response than taller touring sizes
- Warm-weather road use where grip matters more than max sidewall cushion
Performance
235/40R18 Tire Size
Overall Diameter
25.40in
Affects ride height, gearing, and speedometer accuracy.
Section Width
9.25in
Affects traction footprint and steering effort.
Sidewall Height
3.70in
Influences ride comfort and off-road compliance.
Circumference
79.80in
Determines distance traveled per wheel revolution.
Revs Per Mile
794
Used for speedometer and gearing calculations.
Wheel Diameter
18in
Determines wheel compatibility and fitment.
235/40R18 is a lower-profile performance size built around sharper steering response and a wider contact patch on an 18-inch wheel. At roughly 25.4" overall with about 3.7" of sidewall, it favors dry-road grip and turn-in over the tall cushion of truck or touring sizes. Products indexed for this size include highway-terrain, performance, and winter options depending on actual coverage. Tradeoffs include a firmer ride and more sensitivity to potholes — confirm wheel diameter and speed rating before swapping.
- Strong fit for sporty road use where steering response and dry grip matter more than max sidewall cushion.
- Indexed products include 3 brands and 25 full-spec rows.
- Tradeoffs may include ride comfort, winter traction, and pothole sensitivity versus taller touring sizes.
At a Glance
Nominal dimensions calculated from the 235/40R18 size code (235/40R18). Load range and speed rating come from indexed manufacturer products when available. Our OEM database records this size across 10 vehicle models and 80 factory configurations from model years 2006–2017, 2021–2026.
Rim Diameter Calculated
18"
Section Width Calculated
235 mm
Aspect Ratio Calculated
40%
Load Range Manufacturer
SL, XL
Speed Rating Manufacturer
V, W, Y
Construction Standard
Radial
Applicable Tire Categories
Based on this size’s editorial category and exact-size product metadata. A size may support several uses without every product in the size belonging to every category.
Consider Another Size If
- Ride comfort on rough city streets is your top priority
- You need dedicated winter traction without a separate tire set
- You want lower replacement cost and longer tread life over peak grip
Real-World Impact
- Sharper turn-in and more direct steering feedback
- Lower sidewall means more pothole and curb sensitivity
- Usually firmer ride and more road noise than touring sizes
Verified Vehicle Examples
Documented OE or commonly associated platforms for 235/40R18.
-
Honda
Civic
Si
2022–2026
-
Hyundai
Elantra
N Line
2021
-
Kia
K4
GT-Line
2025–2026
-
Porsche
Boxster
Boxster S
2012
-
Toyota
GR Corolla
Core / Circuit Edition
2023
-
Volkswagen
CC
Executive
2013–2017
Documented fitment mappings for research — confirm the door placard, wheel diameter, and load/speed markings before treating any vehicle as a guaranteed fit.
Real Tires Available in This Size
Indexed manufacturer models confirmed in exact size 235/40R18
Manufacturer-provided product/spec data from Michelin, Goodyear, BFGoodrich, Toyo, and Falken where available.
Performance
Celsius Sport
235/40R18 · 95Y · Load Range XL
Performance
Extensa Hp II
235/40R18 · 95W · Load Range XL
Performance
Azenis FK460 A/S
235/40R18 · 95Y · Load Range XL
Performance
Ziex ZE960 A/S
235/40R18 · 95W · Load Range XL
Performance
Eagle F1 All Season
235/40R18 · 95Y · Load Range XL
Performance
Eagle F1 Asymmetric 2
235/40R18 · 95Y · Load Range XL
Best Options by Use Case
Highway / Touring
Better for road noise, towing stability, and long highway mileage.
Top pick
Goodyear Assurance Finesse®
Other options
- Goodyear Assurance Maxlife®
- Goodyear Assurance Maxlife®2
Performance
For sharper steering response, higher-speed ratings, and sportier road feel.
Top pick
Goodyear Eagle® F1 All Season
Other options
- Goodyear Eagle® F1 Asymmetric 2
- Goodyear Eagle® F1 Asymmetric 6
Winter
Use dedicated winter tires when snow and ice grip matter more than tread toughness.
Top pick
Toyo Observe G3-Ice
Other options
- Toyo Observe Gsi-6
Product Spec Comparison
Compare tread depth, weight, max load, pressure, and revs per mile for full-spec 235/40R18 products.
FAQ
Is 235/40R18 good for performance driving?
235/40R18 can be a strong choice for performance driving when you want sharper steering and a wider contact patch on an 18-inch wheel (about 25.40" overall, ~3.70" sidewall). It is less ideal if ride comfort, winter traction, or lower replacement cost matter more than dry-road response. Match speed rating and load index to the vehicle placard.
What vehicles use 235/40R18 tires?
235/40R18 is commonly seen on sporty cars, performance trims, and plus-size upgrades that keep the same 18" rim diameter. Exact OE fitment varies by year and package — treat vehicle lists as directional, not a guarantee. Confirm wheel width, offset, and speed rating before switching.
What load ranges are available?
Indexed products for 235/40R18 include load ranges such as XL and SL, depending on brand and model. Load capacity still comes from the load index and inflation table on the specific tire — not the size code alone. Match the load range to your GVWR and intended payload or towing use.
Which brands make 235/40R18 tires?
Indexed master-database coverage for 235/40R18 includes Toyo, Falken, and Goodyear. Availability still varies by load range, tread type, and season — check the product cards and full-spec table on this page for models currently listed.
How does 235/40R18 compare to 245/40R18?
235/40R18 measures about 25.40" overall versus 25.72" for 245/40R18 (-0.3" / -1.2%). The shorter size usually trims rotational mass and can raise the speedometer reading relative to actual speed, with less ground clearance. Always check fender clearance and load rating before switching.
What is the load capacity of 235/40R18?
Load capacity depends on the exact tire, load index, and inflation pressure — not the size code alone. Check the manufacturer load table and your vehicle placard when setting pressure or carrying heavy loads. If multiple load ranges exist for this size, choose the one that meets or exceeds the placard requirement.
Formula & Methodology
Every dimension on this site is computed in code from the tire size label — we do not scrape or hand-copy manufacturer spec sheets for overall diameter or circumference.
- Parse the size label. Metric sizes (e.g. 275/70R18, LT265/75R16) and flotation sizes (e.g. 33x12.50R15) are parsed into section width, aspect ratio, construction type, and bead-seat wheel diameter.
- Derive nominal dimensions. Sidewall height = section width × aspect ratio ÷ 100. Overall diameter = wheel diameter + 2 × sidewall height. Rolling circumference = π × overall diameter. Revs per mile = 63,360 ÷ circumference (inches per mile). Revs per km uses the same circumference converted to millimetres.
- Compare two sizes. Diameter, width, sidewall, and circumference deltas are signed differences between parsed specs. Speedometer error assumes the cluster is calibrated to the reference tire: true speed = indicated speed × (new diameter ÷ reference diameter). Static ground clearance change uses half the overall-diameter delta at each axle.
Rim diameter shown on this page is always 18" — the bead-seat diameter encoded in 235/40R18.
Safety & Fitment Limitations
- Calculated dimensions are nominal planning baselines from the size code — mounted tires can differ with tread depth, inflation, rim width, and production tolerance.
- Always confirm 235/40R18 against the door placard or owner’s manual, including load index, load range, and speed rating for your vehicle.
- Changing diameter affects speedometer accuracy, gearing feel, ABS/traction calibration, and clearance at fenders, control arms, and the spare well.
- Vehicle examples and product cards are not a guarantee of fitment. Verify wheel diameter (18"), offset, and suspension setup before buying.
Sources & Review
Dimensions are calculated from the tire size label; product rows and fitment mappings come from documented manufacturer and OE sources where available.
- Curated tire-size dataset. Production tire labels, vehicle categories, and optional load/speed ratings maintained in our internal catalog. Only field-valid sizes that round-trip through the parser are published.
- ISO / ETRTO service-description tables. Load index → maximum load (kg) and speed rating symbol → maximum sustained speed (km/h) mappings embedded in our rating resolver, aligned with widely published ETRTO reference values.
- Nominal tire geometry formulas. Overall diameter, sidewall, circumference, and revolutions per mile are calculated from the size code using standard metric and flotation geometric relationships — the same relationships used across the tire industry for nominal sizing.
- Documented OE fitment mappings. Vehicle make, model, trim, and year-range associations linked to specific tire sizes in our fitment data. These are representative applications for research — always confirm against your door placard.
Next step: compare 235/40R18 before changing tire sizes
Compare 235/40R18 against nearby sizes like 245/40R18, 235/45R18, 255/35R19 to check diameter change, speedometer impact, clearance, and fitment tradeoffs.