Tire Tread Depth for Kingston Drivers, From Ontario's Legal Limit to Winter Grip
Tire tread depth in Ontario must not drop below 1.5 mm: Ontario's Ministry of Transportation Driver's Handbook says to replace tires with less tread than that, or once the wear indicators meet the road.
For wet or snowy roads, the advice in Riding on Air, Transport Canada's tire safety guide, is to "replace your tires before they reach the minimum tread depth." The legal line is a floor to plan ahead of, not a number to drive down to.
Winter brings its own figures, from Transport Canada and from Quebec, and Ontario's safety certificate inspection for a used vehicle sets a separate line that is stricter than the legal limit.
Choosing or pricing a new set is a different job from measuring the old one, so this article names no tire brand, size or price.
Key Takeaways
Ontario's legal minimum tire tread depth is 1.5 mm in the MTO Driver's Handbook, and Jim Thompson Chrysler in Kingston treats that line as a floor to plan ahead of, not a target. The MTO Driver's Handbook says "Replace tires when the tread is less than 1.5 millimetres deep," and Transport Canada's tire safety guide, Riding on Air, says to "replace your tires before they reach the minimum tread depth" for the best traction in wet or snow.
The wear bar marks the last call for a tire, not the target. A tire must be replaced once the tread wears level with the indicator, according to Transport Canada's tire safety guide, Riding on Air, which puts the indicator at 1.5 mm, or 2/32 of an inch.
For snow-covered roads, Transport Canada's winter tire guidance draws the line at 4 mm, and Québec.ca's winter tire page recommends at least 4.8 mm in winter. Both are winter recommendations rather than Ontario law, and the SAAQ's winter preparation page measures its 4.8 mm across the full width of a used winter tire at installation.
Ontario's Safety Standards Certificate inspection has a stricter tread line of its own. The MTO's Passenger/Light-Duty Vehicle Inspection Standard rejects a tire with less than 2 mm of tread at its shallowest point, measured in a major groove.
Jim Thompson Chrysler in Kingston suggests measuring a stored winter set in swap season, before it goes back on. A set checked before the changeover leaves time to replace it ahead of the first snowy commute on Highway 401.
What Is the Legal Tire Tread Depth in Ontario?
The legal tire tread depth in Ontario is at least 1.5 mm: Ontario's tire regulation, Regulation 625 under the Highway Traffic Act, says a tire shall not be worn so far that less than 1.5 mm of tread depth remains, or so far that the tread wear indicators contact the road.
The MTO Driver's Handbook gives drivers the same limit: "Replace tires when the tread is less than 1.5 millimetres deep."
Adjacent Grooves at Three Points Around the Tire
Ontario's tire regulation measures the limit in "any two adjacent major grooves at three equally spaced intervals" around the tire.
Ontario's tire regulation defines siping as small straight, angled or curved slits, other than grooves, cut or moulded into the tread surface, and says siping does not count as tread.
Front Tires on Heavier Trucks
Heavier trucks have a deeper line for their front tires: the MTO Driver's Handbook says vehicles weighing more than 4,500 kg "must replace their front tires when tread is less than three millimetres deep."
Ontario's tire regulation applies the 3 mm front-tire rule to vehicles with a gross vehicle weight rating over 4,500 kg.
The Safety Standards Certificate Line
A used vehicle going through Ontario's Safety Standards Certificate inspection faces a stricter tread line. The MTO's Passenger/Light-Duty Vehicle Inspection Standard, used for that certificate, rejects a tire with less than 2 mm of tread at its shallowest point.
The MTO inspection standard has the inspector find the shallowest spot and measure it in a major groove with a tread depth gauge, never on top of a wear bar.
The MTO inspection standard's 2 mm figure is a certificate test, separate from the everyday limit for driving.
When Do the Wear Bars Say a Tire Is Done?
The wear bars say a tire is done once the tread has worn level with them, according to Transport Canada's tire safety guide, Riding on Air. Riding on Air describes each indicator as "a small raised bar that runs across the grooves of the tire tread," and it marks the lowest depth the tread is allowed to reach.
Riding on Air says "Normally, there are six tread wear indicators spaced evenly around the tire," and it puts each indicator at 1.5 mm, or 2/32 of an inch.
Transport Canada's winter tire guidance adds a caution of its own: "Some tires may come with tread-wear indicators that are 2mm." Whatever depth the bars on your tires sit at, tread that reaches them is due for replacement.
The Bar Is the Last Call, Not the Target
A bar sitting flush with the tread is the last call, not a reading to aim for.
For the best traction in wet or snow, Riding on Air's advice is to change tires before the tread gets down to the minimum. Jim Thompson Chrysler suggests planning new tires while there is still tread standing above the bar.
Riding on Air also says "As a tire wears, traction is reduced." On a slippery Kingston road, worn tread is one concern and an ABS light that stays on is another, and each is worth raising with our service team.
What Is a Safe Tire Tread Depth for Snow and Winter Roads?
For a safe tire tread depth on snow-covered roads, Transport Canada's winter tire guidance sets its line at 4 mm, saying not to use tires "worn close to 4 mm (5/32) tread depth on snow covered roads."
Québec.ca's winter tire page, from the Government of Quebec, sets a higher winter mark: "the recommended depth is at least 4.8 mm."
The SAAQ's winter preparation page, from the Société de l'assurance automobile du Québec, gives used winter tires "at least 4.8 mm (6/32 in)" of tread across the full width, measured at installation.
For drivers who cover long distances over the winter months, the SAAQ's winter preparation page warns that "vehicle traction can decrease quickly once treads get worn down to that point."
The 4 mm and 4.8 mm figures are winter recommendations from Transport Canada and Quebec, not Ontario law.
Tread tells you whether a set can go back on; timing is a separate question, and the right moment for winter tires in Kingston follows the temperature more than the calendar.
Swap Season in Kingston
Swap season is the moment to measure, because a winter set coming out of storage is about to spend months on Kingston's salted, snowy roads.
Lay the set out on the garage floor and check each tire before the changeover, so a set close to Transport Canada's 4 mm line can be replaced before the first snowy commute on Highway 401.
A tire that feels fine on Princess Street at city speeds still has to cope with slush on the 401 once the season turns.
Which Tread Figure Matters on a Snowy Highway 401 Commute?
On a snowy Highway 401 commute, the legal floor is the MTO Driver's Handbook's 1.5 mm, and the winter line is the 4 mm below which Transport Canada's winter tire guidance says not to use tires on snow-covered roads.
Knowing both numbers turns a tread check from guesswork into a quick decision you can make in your own driveway.
A Driveway Check Before the First Snowy Commute
You step out to the driveway before your first snowy commute, a tread gauge in one hand and your keys in the other.
You know where the bars sit in the grooves, which number is the law and which one is the winter line.
If the gauge reads close to the bar, you also know your next step: a service request before the snow, not after it.
If it reads well above the winter line, you back out and head for the 401 knowing what is under you.
What Does a Tire Tread Depth Chart Look Like for Ontario Drivers?
A tire tread depth chart for Ontario drivers sets the legal limit, the certificate line and the winter recommendations side by side, each credited to the body that publishes it. The tread depth of a new tire varies by tire, so the chart starts at the replacement lines rather than at a new-tire figure.
Tread depth figures from Ontario, Transport Canada and Quebec sources, read October 27, 2026; each body sets its figure for a different purpose.
Depth | What it marks | Who says it |
|---|---|---|
1.5 mm | Ontario's legal replacement line for tires | The MTO Driver's Handbook |
3 mm | Replacement line for the front tires of vehicles weighing more than 4,500 kg | The MTO Driver's Handbook |
2 mm | Safety Standards Certificate reject line, at the tire's shallowest point | The MTO inspection standard |
4 mm | Tires worn close to this should not be used on snow-covered roads | Transport Canada's winter tire guidance |
4.8 mm | Recommended minimum for winter | Québec.ca's winter tire page and the SAAQ's winter preparation page |
In the MTO Driver's Handbook, 1.5 mm and 3 mm are Ontario's tire limits for driving, while the 4 mm and 4.8 mm figures are winter advice from Transport Canada and Quebec.
How to Measure Tire Tread Depth at Home
To measure tire tread depth at home, read the depth in the main grooves with a tread depth gauge, look at the wear bars, and repeat the check at several spots on every tire.
With a Tread Depth Gauge
Transport Canada's "Winter Tire Pressure" video says to check tread with a tread depth gauge: put the gauge's tip into the tread grooves and read the measurement.
Measure in a main groove rather than on a wear bar, the way the MTO inspection standard has inspectors do it, and take readings at three points spaced evenly around the tire, as Ontario's tire regulation does.
With the Wear Bars
Run a fingertip along a main groove until you meet one of the raised bars Riding on Air describes, then compare the tread on either side with the top of the bar.
Tread standing above the bar has not reached Riding on Air's minimum yet; tread level with the bar has.
With a Quarter, for Snow Grip
Québec.ca's winter tire page gives owners a quick snow-grip check: "place a quarter in a groove with the caribou's nose pointing down."
If the caribou's snout is visible, Québec.ca's winter tire page says the tire will not hold well in deep snow. The quarter test is a snow-grip check from Québec.ca, not a measure of Ontario's legal limit.
More Than One Groove
Québec.ca's winter tire page adds: "Check several grooves in different locations for tire wear."
Riding on Air also asks drivers to inspect tires regularly for damage and for excessive or uneven wear. A single reading in the middle of the tread can miss wear that sits along one edge.
Tire pressure is a separate check from tread, with its own gauge and its own numbers.
Why Does Tread Wear Unevenly, and Who Should Look at It?
Uneven tread wear can come from improper wheel alignment or a tire imbalance, according to Riding on Air. Riding on Air says to have the tires "inspected by an expert who can recommend the best corrective action."
If your tires show uneven wear, mention it in your service request so our service team knows to look. Tire rotation is one of the services set out on the page for our service centre in Kingston.
The 2026 Ram 1500 Owner's Handbook lists a tread depth difference of 2/32 in (1.5 mm) or more among its reasons to rotate the tires, next to a distance interval. The 2026 Ram 1500 Owner's Handbook also says to rotate at the first sign of irregular wear, even before the oil change indicator comes on.
The tread-difference and irregular-wear triggers are printed for the 2026 Ram 1500 alone, and another model's schedule may differ.
When tread depths differ between tires, Transport Canada's winter tire guidance says the tires with the deepest tread go on the rear of the vehicle.
Low Tread? Request Service, or Call Our Team First
With tread still above the wear bar, request service; with tread that has reached the bar, call our service team first.
Use Request Service to name a preferred date, and add the reading from each tire. A request turns into an appointment once our service team confirms the time.
If the reading says a new set is due, the tire search runs through our Tire Finder.
If the Tread Has Reached the Bar
A tire worn level with the bar is due for replacement in Riding on Air's terms, and one below 1.5 mm is past the MTO Driver's Handbook's limit. For a vehicle on tires like that, contact our service team to talk through how it gets to us.
Signature Service, a service request and a phone call are not emergency help, and Signature Service is not the way to move a vehicle on tires worn to the bar.
From a Driveway Reading to JTC Signature Service
Got a reading still above the wear bars and a full workday ahead? When you call, ask our service team about JTC Signature Service for a vehicle that is safe to drive.
Signature Service means we collect a vehicle that is safe to drive, look after the tire work and bring it back, so your day carries on while the work gets done.
Our team sets the pick-up and drop-off times with you over the phone, Monday through Friday and based on availability, for addresses within Kingston city limits.
A loaner is subject to availability, and some customers do not need one at all; call our service team, or send us a message on the Contact page for more details.
Signature Service is for a vehicle whose tires still sit above the wear bars.
Frequently Asked Questions
When Do Tires Have to Be Replaced in Ontario?
Tires in Ontario have to be replaced below 1.5 mm of tread, or once the wear indicators meet the road, according to the MTO Driver's Handbook, which says "Replace tires when the tread is less than 1.5 millimetres deep." The MTO Driver's Handbook sets 3 mm for the front tires of vehicles weighing more than 4,500 kg.
Do Winter Tires Need More Tread Than Ontario's Legal Minimum?
Yes: Transport Canada's winter tire guidance says not to use tires with less than 4 mm of tread on snow-covered roads, or tires worn close to 4 mm. Québec.ca's winter tire page recommends at least 4.8 mm in winter, a Quebec recommendation rather than an Ontario law.
Where Do You Find the Tread Wear Indicators on a Tire?
Tread wear indicators sit in the grooves: Transport Canada's tire safety guide, Riding on Air, describes each one as "a small raised bar that runs across the grooves of the tire tread." Riding on Air says there are normally six, evenly spaced around the tire, and it puts the indicator at 1.5 mm, or 2/32 of an inch.
What Tread Depth Fails an Ontario Safety Certificate?
Tread under 2 mm at the shallowest point fails, under the MTO's Passenger/Light-Duty Vehicle Inspection Standard, which has the inspector measure in a major groove and never on a wear bar. The Safety Standards Certificate line in the MTO inspection standard is stricter than Ontario's legal limit for driving.
What Does the Quarter Test Show on a Winter Tire?
The quarter test shows whether a winter tire grips in deep snow: Québec.ca's winter tire page says to "place a quarter in a groove with the caribou's nose pointing down." A visible snout means poor grip in deep snow, by Québec.ca's winter tire page, so the quarter is a snow check rather than a test of Ontario's legal limit.
Find Your Tire Tread Depth Before Winter in Kingston
A tire tread depth reading, set beside the wear bars and the winter figures, shows whether a set is ready for the season or due for replacement.
Request Service before the snow settles in, and put each tire's reading in the request so our service team sees what you found.
Visit us at 805 Gardiners Road, Kingston, ON K7M 7E6
Request Service to ask for a preferred date and time. A request is not a confirmed appointment until our service team contacts you.
Local: (613)-389-4426 Sales: (877)-251-9249 Parts: (888)-711-5309 Service: (888)-713-0742
About the Author:
Kerry Irven is the Vice President of New and Used Automotive Operations for Heighton Automotive Group, a family-owned and operated automotive group serving communities across Eastern Ontario. Kerry began his automotive career in new-car sales, building his experience on the showroom floor and working his way through multi-store dealership operations.
With over 25 years in the automotive industry, Kerry has helped grow automotive businesses from one location with 40 to 50 vehicles in stock to more than 500 vehicles across 10 rooftops. His hands-on background in both new and used-vehicle operations gives him a practical understanding of what customers look for when shopping for their next vehicle.
Throughout his career, Kerry has always been actively involved in staff coaching and in understanding customer wants and needs, helping ensure the businesses he works with continue to adapt to what customers are truly looking for.
One of the most exciting chapters of his career has been the shift into modern automotive marketing, embracing new technology, transparent pricing, customer-first inventory strategies, and new ways to create a better vehicle-shopping experience.
Kerry has completed extensive automotive training, including certification through the Ontario Motor Vehicle Industry Council, involvement with the Used Car Dealers Association of Ontario, Canadian automotive dealer training, and multiple customer service courses.
Born and raised on a farm, Kerry has always valued family, hard work, and a practical, down-to-earth approach. Joining Heighton Automotive Group and working alongside Thomas Heighton and family, along with managing partners Kyle Lothian and Martin Gougeon, has allowed him to bring those same values into the car business. It has also allowed Kerry to continue following a simple philosophy: treat every customer exactly the way he would want to be treated.
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