235/40R18 tires
235/40R18 is the size of the hot compact. The Honda Civic Si from 2017 to 2023 and the Civic Sport and Touring from 2017 use it, as do the 2013 to 2018 Ford Focus ST and the Cadillac CT4. It is also the front size on the 997-generation Porsche 911 and the 987 Boxster and Cayman on 18-inch wheels. Below are real prices for 158 tires in stock, three picks with their size-specific specifications, and how to buy for a Porsche front axle.
Yes, this fits your Porsche Boxster/Cayman. 235/40R18 is the original size on the front axle on the 2005-2012 Porsche Boxster/Cayman.
The sticker inside the driver's door is still the final word, because trim and wheel package can change the size. Back to every Porsche Boxster/Cayman size.
What 235/40R18 tires cost
Kumho Ecsta PA51
UHP all-season XL, 95W, 45,000-mile warranty, UTQG 500 A A.
Listed as Kumho Ecsta PA51 235/40ZR18 95W All Season Passenger Tires
Continental ExtremeContact DWS06 Plus
UHP all-season XL, 95Y, 50,000-mile warranty, UTQG 560 A A.
Listed as Continental ExtremeContact DWS06 PLUS 235/40ZR18 95Y Passenger Tires
Continental ContiProContact
All-season, 91W, 40,000 miles in W, UTQG 400 A A.
Listed as Continental ContiProContact 235/40R18 91W All Season Passenger Tires
Prices are per tire, before mounting and balancing. A set of four in the mid range comes to roughly $409 to $748, and a brand rebate can take another $50 to $110 off, see this month's deals.
Cheapest 235/40R18 right now
Lionhart LH-503 235/40R18 95W All Season Passenger Tires
$71.96per tire $143.92 for 2 tires (one axle)
158 tires in this size, priced straight from SimpleTire's own product feed, read 13 November 2026. Stock and prices move daily, so check the shop for today's figure.
See every 235/40R18 tire in stock at SimpleTire
Civic Si and Focus ST: one set or two
These are cars bought by people who enjoy driving, and many owners run a dedicated summer tire in the warm months and an all-season or winter tire the rest of the year. Our three picks are all-season tires, which makes them the choice for a single-set car. Two of them are ultra-high-performance all-seasons with extra-load ratings, which steer and brake closer to a summer tire than a touring all-season does, and keep usable grip in light snow.
On a front-wheel-drive car with this much power the front tires wear much faster than the rears. Rotate them regularly, or plan to buy fronts on their own.
Porsche front axle: staggered and N-rated
On a 911 or Boxster this is only the front tire; the rear is wider, so buy the set as one model and replace by axle. Porsche approves specific tires, marked with an N and a number on the sidewall, which are developed for the car's handling balance. A non-N tire will fit and is legal, but Porsche recommends against mixing N and non-N tires on the same car.
What the numbers on the sidewall mean
A 235/40R18 tire is 235 millimeters wide, its sidewall is 40 percent of that (about 3.7 inches tall), and it mounts on a 18-inch wheel. That works out to an overall diameter of roughly 25.4 inches. Every replacement has to match all three numbers, and the load index and speed rating on the placard inside the driver's door have to be met or exceeded.
In this size our picks are marked 91W on the Continental ContiProContact (1,356 lb per tire, rated to 168 mph). The first number is the load index, the letter the speed rating; a tire with equal or higher values than your placard is fine, a lower one is not.
Our guide on reading a tire size walks through the markings, and this one lists every load index and speed code.
Our three picks, side by side
One tire at each price level from what the retailer stocks in this size, with the mileage warranty and UTQG grades as published by the manufacturers and their retailers. Treadwear is the number to compare: it is a relative wear rate, so 700 should last roughly twice as long as 350 on the same car.
| Kumho Ecsta PA51 | Continental ExtremeContact DWS06 Plus | Continental ContiProContact | |
|---|---|---|---|
| Price per tire (Nov 13, 2026) | $129.86 | $192.99 | $179.20 |
| Set of four | $519.44 | $771.96 | $716.80 |
| Service description in 235/40R18 | — | — | 91W |
| Mileage warranty | 45,000 mi on non-OE tires | 50,000 mi; 25,000 mi on staggered fitments | 80,000 mi for S and T speed ratings; 60,000 mi for H; 40,000 mi for V and W |
| UTQG treadwear / traction / temperature | 500 AA A (typical, varies by size) | 560 AA A (typical, varies by size) | 400 AA A (typical, varies by size) |
| Season | Ultra-high-performance all-season | Ultra-high-performance all-season | All-season |
| Extras | — | SportPlus Technology | — |
Kumho Ecsta PA51, $129.86. A low-cost way into an ultra-high-performance all-season: in this size an XL 95W with 11/32 inch of tread, graded 500 AA A and warranted for 45,000 miles on non-OE tires. Our pick for a Civic Sport that is driven sensibly.
Continental ExtremeContact DWS06 Plus, $192.99. The best all-around tire here for a Civic Si or Focus ST: an XL 95Y with a 560 AA A grade, a 50,000-mile warranty and Continental's road-hazard and trial program. It is the lightest of the three at 22 pounds, tied with the Continental touring tire.
Continental ContiProContact, $179.20. Continental's comfort all-season in a standard-load 91W version. Its warranty is tied to speed rating, and in this W-rated size it is 40,000 miles, with a 400 AA A grade. Choose it for a quieter ride on a Civic Touring or CT4 rather than for mileage.
What 235/40R18 tires cost across the whole range
Of the 215 tires listed in this size, 158 are in stock today. The lowest price is the Lionhart LH-503 at $71.96, a 95W tire. The median is $155.10; a third of the tires cost $102.26 or less, and the top five percent start above $292.08. Those are per-tire prices before mounting and balancing, which adds $15 to $45 per tire at most shops, read from the retailer's feed Nov 13, 2026.
The same tires in neighboring sizes
The Kumho Ecsta PA51, our budget pick here at $129.86, is also stocked in 215/45R17 ($119.99), 205/50R16 ($101.96), 215/45R18 ($119.96) and 225/45R18 ($108.96). The Continental ExtremeContact DWS06 Plus, our mid-range pick here at $192.99, is also stocked in 215/45R17 ($176.99), 235/40R19 ($241.99), 215/45R18 ($189.99) and 225/40R18 ($168.99). The Continental ContiProContact, our premium pick here at $179.20, is also stocked in 205/55R16 ($142.24), 195/65R15 ($122.08), 225/60R18 ($174.96) and 245/40R18 ($257.40). Useful if your vehicle came with a different wheel package, or if you are comparing an upsize: the same tire usually costs more per inch of wheel, not per inch of rubber. Prices per tire, from the retailer's feed Nov 13, 2026.
Winter and this size: summer tires are not winter tires
Many tires sold in this size are summer tires, and the manufacturers advise against driving them in near-freezing temperatures: the compound hardens, grip drops sharply and the tread can crack. They also carry no M+S or 3PMSF marking, so a car on summer tires fails Colorado's Passenger Vehicle Traction Law outright on the 126 miles of I-70 between Dotsero and Morrison, in force from September 1 to May 31, unless it is all-wheel drive with at least 3/16 inch of tread; fines start at $130. If the car is driven year-round in a state with real winters, either run an all-season or all-weather tire in this size or keep a second set of winter tires, often on a smaller, narrower wheel that is also less expensive.
None of our picks in this size, the Kumho Ecsta PA51, Continental ExtremeContact DWS06 Plus and Continental ContiProContact, carries the 3PMSF symbol; for that, look at the all-weather and winter tires.
Vehicles that came with 235/40R18
- Honda Civic Si (2017-2023)
- Honda Civic (2016-2021, Sport/Touring)
- Honda Civic (2022-2024, Sport/Touring)
- Ford Focus ST (2013-2018)
- Cadillac CT4 (2020-2024, 18 in)
- Porsche 911 (2005-2011, 997 front)
- Porsche Boxster/Cayman (2005-2012, 987 18 in front)
The Porsche entries are front-axle sizes of staggered sets, and earlier Civic trims used 16- and 17-inch wheels; check the placard.
Which type of 235/40R18 tire?
Frequently asked questions
How much do 235/40R18 tires cost?
Expect $72–$102 per tire for a budget brand, $102–$187 for a mid-range tire like the Continental ExtremeContact DWS06 Plus, and $187–$292 for a premium tire like the Continental ContiProContact. A set of four therefore starts at about $288. Add roughly $15 to $45 per tire for mounting and balancing.
What vehicles use 235/40R18 tires?
235/40R18 is original equipment on Honda Civic Si (2017-2023), Honda Civic (2016-2021, Sport/Touring), Honda Civic (2022-2024, Sport/Touring), Ford Focus ST (2013-2018), Cadillac CT4 (2020-2024, 18 in), Porsche 911 (2005-2011, 997 front) and Porsche Boxster/Cayman (2005-2012, 987 18 in front), among others. Always confirm with the sticker inside your driver's door, because trim levels and wheel packages can change the size.
What is the best 235/40R18 tire?
For most drivers our mid-range pick, the Continental ExtremeContact DWS06 Plus, is the sweet spot of price and tread life. If you keep the vehicle a long time or drive in heavy rain and snow, the Continental ContiProContact is worth the extra. On a tight budget the Kumho Ecsta PA51 is a sound choice.
Can I replace just one or two 235/40R18 tires?
On a front- or rear-wheel-drive car, yes: replace in pairs on the same axle and put the newer pair on the rear. On all-wheel-drive vehicles most makers want all four replaced together, or a new tire shaved to match, because a difference in circumference strains the drivetrain.