RV tires through winter storage

Tire pressure moves with temperature, and the rule is simple: for every 10°F the air cools, the pressure drops about 1 to 2 psi. A tire filled to its spec on a warm September afternoon reads several pounds low on a February morning, and the reading is accurate, the air just condensed. Drive that underinflated tire in the spring and it runs hot, and heat is what kills tires from the inside out.

Fill to the cold spec. The correct pressure is what the tire should read when cold, meaning before it has been driven that day. Fill to the sidewall-cold number or the inflation table in the owner's manual before parking, when the tire is cold. Do not "compensate" for winter by over-inflating, the spec is already the cold spec, and overfilling puts the center of the tread on the road and strains the sidewalls.

Check monthly, and top off as the temperatures fall. A tire that was correct in October will read low in December, and that is expected, not a leak. Add air each month as needed and keep it at the cold spec. It is also the moment each month when you can glance at the sidewalls for the cracks covered later in this guide.

Park any tire under load and the rubber flattens where it meets the ground. Drive it soon after and it rounds back out. Let it sit for months, especially in the cold, and that flattened section of the casing takes a set, and the thump follows you down the highway.

The honest timeline. Under ordinary conditions, a parked RV develops a noticeable flat spot after about a month of sitting. Cold weather hurries this along considerably, because cold rubber loses the elasticity it needs to spring back. Below about 40°F, a loaded tire on a hard surface can show a measurable flat spot in two to four weeks; below freezing, some tires can set within two to three weeks under full load on cold concrete. In cold or heavily loaded conditions, permanent deformation can begin in as little as 90 days of static storage.

Temporary and permanent are not the same. A temporary flat spot rounds out after the tires warm and you drive ten or fifteen miles. A permanent flat spot is different: the internal steel belts and nylon overlays have taken a set, the tire is slightly egg-shaped, and it will thump and vibrate for its entire remaining life, generating heat every mile. If a set of tires parked cold for months comes out badly out of round, replacement is the honest answer, not hope.

The right way to take the weight off

The cleanest solution is to get the vehicle's weight off the tires entirely. That means heavy-duty jack stands rated for the RV's weight, placed on the frame, not on thin floor supports, storage compartments, or the axles themselves. Two cautions that owners often get wrong:

• Leveling and stabilizing jacks are not a substitute. Per the RV industry standard, those jacks are not designed to carry the full weight of the chassis. Using them to lift the tires clear can stress the frame and the slide-out structure. Jack stands on the frame are the tool for this job, and leveling jacks are at most a supplement.
• Do not let the suspension hang. If the frame is fully supported and the tires hang free, the suspension is over-extended for months, which can let springs sag and, on some RVs, misalign doors and slide-outs. The balanced approach many owners settle on: support the frame with jack stands so it carries roughly 95 percent of the weight, and lower the tires to barely touch a wooden board. The rubber is unloaded, the suspension rests normally, and the concrete never touches the tread.
• The wood matters even when tires stay on the ground. Concrete slowly leaches antioxidants out of tire rubber on contact, and moisture wicks up through it. A plywood pad under each tire is a cheap barrier, though it does not by itself stop flat spotting, which is a matter of load and time, not surface.

If you cannot get the weight off

Not everyone can jack their RV, and that is a common reality. Three partial measures, in order of value: keep the tires at the correct cold pressure (an underinflated tire flattens faster and worse). Move the RV a few inches forward or backward on the blocks every few weeks so the contact patch shifts to fresh rubber and the old spot can relax. Let the tires rest on plywood pads. None of these fully replaces unloading the tires, but together they extend the safe window meaningfully.

If the RV sits outside, the tires face two enemies a cover can help with: ultraviolet light, which is the quiet killer of sidewall rubber, and trapped moisture, which rots it. A purpose-made tire cover is ventilated on purpose. Use fabric that breathes.

• Breathable covers only. The fabric is made to let moisture evaporate while shading the sidewall from UV.
• Never plastic sheeting or a wrapped tarp. That turns the cover into a greenhouse at the sidewall, holding condensation against the rubber and the wheel all winter.
• Check the inside face too. UV reaches a tire from underneath as well, so the inner sidewall can crack when the outside looks fine. Cracks on the inner face are the sun's work too, and they count the same.

RV tires age by the calendar, not the odometer. A trailer tire can look nearly new with full tread and be structurally done, because the rubber compound degrades from UV light, heat cycling, and time whether you drive 500 miles a year or 5,000. The number that tells you the truth is molded into the sidewall.

• Read the DOT code. Look for the letters DOT followed by a longer string. The last four digits are the week and year of manufacture: a code ending in 2619 means the 26th week of 2019. A code ending in 0924 means the 9th week of 2024.
• Six years is the line. Tire makers, including Goodyear in its published service guidance, call for replacement six years from the date in service, or six years from the DOT date if you cannot prove when the tire was first mounted. At five years, have a tire professional inspect them. Industry practice treats seven years as the firm outer limit for any RV tire regardless of condition.
• Check every tire, including the spare. RV tires are often replaced one at a time, so the dates on one RV's four wheels can differ by years. And the spare sits mounted for just as long as the running tires, so it ages on the same clock and deserves the same check.

What age looks like. On inspection, look for fine radial cracks along the sidewall, small bulges or blisters, a spiderweb of tiny cracks known as dry rot or crazing, and waviness in the tread area that can signal belt separation. Any of those is a replace-now signal, not a schedule-a-trip signal.

Two letters on the sidewall tell you what kind of tire you have and what rules apply. ST stands for Special Trailer, and it is the tire found on most towables, designed specifically for trailer service. LT stands for Light Truck, and it belongs on a tow vehicle or, in some setups, a heavy trailer, but only when it meets the manufacturer's requirements for size, load, and pressure. They use different load and inflation charts, so when someone quotes a pressure for your trailer tire, the correct figure depends on which type you are running.

• Load range vs load index. A letter such as C, D, or E is the load range, a category of construction and inflation capability. A number is the load index, the specific rated carrying capacity. They are related but not interchangeable, and the load index or the stated maximum load is the clearer number on a sidewall.
• Cold pressure is the setting. Pressures are specified cold, before driving. Many ST trailer tires are run at their maximum cold inflation, but the wheel's own rating is the ceiling, exceed it and you risk the wheel, not just the tire.
• Set per axle, and keep the pair equal. The accepted practice is to use the heaviest axle-end weight on the trailer to set the pressure for all the tires on that axle, so both sides of an axle run the same figure. A certified scale gives you the axle weights to do this properly.

Pressure assumes weight. A tire pressured for a correctly loaded trailer is under more stress the moment you exceed its rating, and the 80% margin on tire load is as important as the one on your towing capacity. Run the weight calculator with your real cargo to see where you actually stand.

• Inspect every sidewall for UV cracks, bulges, blisters, dry rot, and belt waviness, including the inner faces and the spare.
• Set cold pressure to spec, checking the DOT date on each tire while you are down there.
• Drive gently for the first miles if flat spots were unavoidable, and feel for a thump that does not fade.
• Re-torque the lug nuts in the first 50 miles after the wheels have been off for the season.
• If any DOT code reads six years or older, budget for tires before the trip, not after it.

The rule that saves most people

Winter does not invent new ways to break a tire, it magnifies the two it already has: load held in one spot, and age. Keep the weight off the rubber, keep the pressure at the cold spec, and read the DOT code once a year. Those three habits cover every failure this guide describes.