Winter tire changeover in Boise: it is the nights, not the snow

People arriving from Denver or Chicago look at Boise's snow total and decide they do not need a winter set. Then they meet January. The Boise winter problem is not depth. It is the number of nights the temperature goes below freezing, and what that does to a road surface that was wet in the afternoon.

The normal Boise winter, in numbers

From the NOAA 1991 to 2020 normals at Boise Air Terminal:

• 19.2 inches of snow a year, falling on 19.4 days with at least a tenth of an inch.
• 6.9 days a year with an inch or more, 1.3 days with three inches or more, 0.2 days with five inches or more, and 0.0 days with ten inches or more.
• 100.9 days a year with a minimum at or below 32 F.
• 18.8 days a year on which the temperature never rises above freezing, and 2.3 days with a minimum at or below 0 F.
• January's normal daily maximum is 37.8 F and December's 37.5 F. December's normal daily minimum is 24.0 F and January's 24.7 F.

Put those together. A normal Boise winter contains about seven days where snow actually accumulates, and about a hundred nights that freeze. The tire decision here is not about wading through drifts. It is about a cold morning on a surface that thawed yesterday.

When it actually gets cold, month by month

Month	Nights at or below 32 F	Days that never rise above 32 F	Normal snowfall
October	3.3	0	0.1 in
November	14.2	1.5	2.6 in
December	24.9	7.5	7.0 in
January	23.9	7.3	5.1 in
February	18.2	2.3	2.8 in
March	10.9	0.1	1.3 in
April	4.5	0	0.3 in

November is the first month that looks like winter, and December and January are the whole of it. October barely qualifies: three freezing nights and a tenth of an inch of snow across the month.

That matters, because the legal calendar does not agree with it. Studded tires become lawful on 1 October and must come off by 30 April, so the window opens about a month before the weather and closes about a month after it. The statute and the mismatch are on their own page.

Our own advice on timing is the boring one: swap on the forecast rather than on the date. The first half of November is when a Boise winter set starts earning its keep, and the last week of April is a deadline rather than a recommendation.

Studs are not the same thing as winter tires, in Idaho law

Worth knowing before you book a swap, because it decides whether any calendar applies to you at all.

Idaho Code 49-121(2)(c) defines a snow tire as "Every rubber tire with tread design or material embedded in the tire to improve winter traction except studded tires", and 49-121(2)(e) defines the studded tire separately. The two are mutually exclusive categories in the statute, and only the studded one has a closed season. A studless winter tire can stay on the car in July as far as Idaho Code is concerned.

For a valley that gets 47.5 days a year at or above 90 F you would not want to, because soft winter compound wears fast in heat. But there is no legal date pushing you.

The plow order is the argument for coming to you

ACHD, not the city, clears every street in Ada County, and it publishes exactly where its crews go first:

"ACHD uses a priority system to determine the roads that need to be cleared first. While residential streets are important, main roads are prioritized because of higher traffic volume and safety concerns. Priority one roads include: Arterial and collector roads; Major intersections; Overpasses and bridges; Areas around hospitals and fire stations; School and railroad crossings; Streets with grades (steepness) over six percent. Priority two includes school bus routes as identified by the public-school districts. Priority three includes residential streets, including cul-de-sacs."

The street your car is parked on is priority three of three. No clearance time is published for priority three and we are not going to invent one. What is published is the order, and the order says the arterial you would drive to the shop on gets cleared before the street you would drive out of.

What goes down: "Our winter operations strategy involves use of materials such as magnesium chloride, salt, and/or sand, and where necessary, plowing. These materials are used in anti-icing (before the storm) and de-icing (during the storm) efforts to ensure the safest condition of the roadway."

We will note that magnesium chloride is named first and stop there. What it does to a wheel finish, a bead seat or a TPMS sensor in this particular valley is not something anyone has published, and we are not going to assert a corrosion effect we cannot cite.

Whether a swap costs you a day depends on how many cars you have

A household with a spare car can drop one at a shop and carry on. A household without one loses a morning. Boise is mostly the former, which changes what we are actually selling here — time rather than rescue.

From the 2020-2024 American Community Survey: 63.0 percent of Boise city households keep two or more vehicles (DERIVED: 41.1 percent with two plus 21.9 percent with three or more). Three or more runs 21.9 percent in the city, 26.3 percent across Ada County, 29.8 percent across the metro, and 32.1 percent in 83709 — the highest of the thirteen ZIP Code Tabulation Areas in our Boise research, and that is the whole population that figure is ranked over.

So the pitch is not that you will be stranded. It is that a two-car household still has to move two cars to a shop twice a year, and we move neither.

What we do, and what we do not

The swap. We come to the address and change your winter and summer sets over. $350 for a set already mounted on its own wheels. $390 for loose tires that have to be mounted on the same wheels and balanced. No separate call-out fee. TPMS reset included where the vehicle supports it at the roadside.

The check that comes with it. An off-season set has by definition been run. We measure tread and read the DOT date code at the visit and either refit the set or tell you it is finished. That is the one case where we handle tires we did not sell you; it is your own set, not a used set bought from somebody.

Storage: no. We do not store tires. Storage needs a building, custody terms, insurance covering your property in our care and a retrieval process, and we have none of those. Plenty of competitors sell it and several publish proper terms for it. We publish none, so we do not sell it. The full reasoning is here.

New tires. If the old set is done, we supply and fit the replacement at the same visit, matched to the door placard. We do not mount tires bought elsewhere and we do not sell used tires.

Where to go next

The studded tire window has the statute and the dates. Hillside addresses covers whether we can work where you park, which matters more in the months this page is about. Idaho inspects nothing covers why a seasonal swap is the only routine look anyone gives your tires here.

For the repair side: mobile tire repair in Boise, a flat, a nail, a slow leak, local prices and who is open today.

Nationally: seasonal changeover, all-season, all-weather and winter tires, when to replace your tires, mixing tire brands, how many tires to replace and why we do not offer tire storage. Our Boise service area covers where we come.

Our price: $350 on wheels, $390 loose

A seasonal changeover at your address is $350 for a set already on its own wheels and $390 for loose tires that have to be mounted on the same wheels and balanced. The visit is inside that price; there is no call-out added afterwards. If the space is not safe to work in when we arrive, nothing is charged.

A mobile puncture repair, if the swap turns up a tire with something in it, is $145 for the first tire and $50 for each additional tire in the same visit. If a tire cannot be repaired, the inspection is charged and the repair is not.

Questions people ask

• Does Boise really need winter tires? That is your call and it depends on where you park and drive. The numbers to decide on: 19.2 inches of snow a year across 19.4 days, only 6.9 days with an inch or more, but 100.9 nights at or below freezing and 18.8 days that never rise above it.
• When should I swap? November is the first month that looks like winter in the normals — 14.2 freezing nights and 2.6 inches of snow, against October's 3.3 and 0.1. Swap on the forecast, not on the date the studded window opens.
• Can I leave winter tires on all summer? Legally, yes, if they are studless: Idaho Code 49-121(2)(c) defines a snow tire to exclude studded tires, and only studded tires have a closed season. Practically, soft compound wears fast in a valley with 47.5 days a year at or above 90 F.
• Will the plow have been down my street? Residential streets, including cul-de-sacs, are priority three of three in ACHD's published order, behind arterials, collectors, major intersections, bridges, hospital and fire-station areas, school and railroad crossings, streets over six percent grade, and school bus routes. No clearance time is published for priority three.
• What does the swap cost? $350 for a set already on its own wheels, $390 for loose tires that have to be mounted and balanced. No call-out fee.
• Will you store my summer set? No. Storage needs a building, custody terms and insurance, and we have none of those, so we do not sell it.