Quick Summary:
- Pull over safely, check warning lights, and photograph tyre and dashboard.
- Use the sealant and inflator kit only for small tread punctures.
- Call roadside assistance for sidewall damage, blowouts, or repeated pressure loss.
- Avoid driving on a flat, it can ruin wheel rims and increase charges.
Many California car hire vehicles no longer carry a spare tyre. Instead, you may find a sealant and inflator kit, sometimes called a tyre mobility kit, in the boot. This is common on newer cars and some SUVs because it saves weight and space. The key is knowing what the kit can fix, what it cannot, and how to protect yourself from avoidable damage or towing costs.
This guide walks you through what to do the moment you suspect a puncture, how to use a sealant and inflator kit step by step, when to stop and call roadside assistance, and how to reduce the risk of wheel, tyre, or underbody damage that can lead to extra charges at return.
If you arranged a car hire for arrival at Los Angeles, you might want to save the details from your confirmation and the location page such as car rental airport Los Angeles LAX so you can quickly reference pickup information if you need support later. If your trip starts further north, details for car rental Sacramento SMF can be equally helpful to keep to hand.
1) First signs of a puncture, what to do immediately
Common signs include a tyre pressure warning light, the car pulling to one side, a flapping noise, vibration through the steering wheel, or a sudden thump followed by rough handling. Act quickly but calmly.
Step 1, slow down smoothly. Take your foot off the accelerator, avoid sharp steering, and do not brake hard unless necessary. If you are on a freeway, signal early and move to the right shoulder when safe.
Step 2, get to a safe stopping place. Prioritise safety over convenience. Ideally stop on level ground, away from traffic, with good visibility. If a shoulder is narrow or unsafe, it can be better to exit the freeway and stop in a car park.
Step 3, turn on hazard lights and secure the car. Put the car in Park, apply the parking brake, and keep passengers away from traffic. In poor visibility, keep lights on.
Step 4, check the tyre without putting yourself at risk. Walk around the vehicle on the side away from traffic if possible. Look for an obvious nail or screw in the tread, a cut, or a tyre that has come off the rim. If you hear loud hissing or the tyre is visibly shredded, do not attempt a sealant repair.
Step 5, document the situation. Take clear photos of the tyre, the wheel rim, and the dashboard warning light. If you later need to discuss damage, these photos can help show you stopped promptly and did not continue driving on a flat.
2) Understand what a sealant and inflator kit can and cannot do
A sealant kit is designed for small punctures in the tread area, typically caused by a nail or screw. It works by injecting liquid sealant into the tyre and then inflating it so the sealant can plug the hole from the inside.
Use the kit only if all of the following are true: the tyre still has some air, the damage appears to be in the tread (the part that touches the road), the puncture is small, and you can safely run the engine to power the compressor.
Do not use the kit if: there is sidewall damage, a blowout, a large tear, the tyre has come off the rim, you have driven on the flat and the sidewall is shredded, or the wheel rim is damaged. In those cases, using sealant wastes time and may complicate later repairs.
Also note that sealant is usually a temporary measure to get you to a safe place or a tyre shop. It is not a permanent fix for long-distance driving across California. Some tyre shops may charge extra to clean sealant, and some tyres cannot be repaired after sealant is used. This is another reason to use it only when appropriate.
3) Step-by-step, using a tyre sealant and inflator kit
Different cars have different kits, but the process is similar. Always follow the instructions on the kit label and in the vehicle manual first, especially for pressure targets and time limits.
Step 1, locate the kit and check contents. It is often under the boot floor. You typically have a compressor, a sealant bottle (or integrated canister), a hose, and sometimes a valve tool. Check the sealant expiry date if visible. If it is expired, skip to calling roadside assistance.
Step 2, prepare the vehicle. Keep the car in Park with the parking brake on. Start the engine if the kit requires power from the 12V socket, because running the compressor on battery alone can drain it quickly.
Step 3, position the valve. Roll the car slightly if needed so the tyre valve is accessible. Remove the valve cap and keep it safe.
Step 4, attach the sealant. If the kit uses a separate bottle, connect it between the compressor hose and the tyre valve. If it is integrated, connect the compressor hose directly to the valve. Ensure the connection is tight to prevent leaks.
Step 5, inject sealant and inflate. Switch on the compressor. Many kits inject sealant first and then inflate automatically. Inflate to the recommended pressure listed on the driver door jamb sticker or kit instructions. Do not exceed the recommended maximum shown on the kit.
Step 6, check for pressure hold. After reaching target pressure, turn off the compressor and wait a few minutes. If pressure drops quickly, the puncture may be too large or the tyre may have other damage. If it will not hold pressure, do not drive, call roadside assistance.
Step 7, drive slowly to distribute sealant. Drive for about 5 to 10 minutes at low speed so the sealant spreads and seals. Avoid hard acceleration, sharp turns, and high speeds.
Step 8, re-check pressure. Stop again in a safe place and re-check with the compressor gauge. If the tyre is still below target, top it up. If it keeps losing pressure, stop driving and call for help.
Step 9, plan the next stop. The sealant repair is temporary. Head to a tyre shop or service area as soon as practical, and tell them sealant has been used. Keep speeds conservative and avoid long freeway stretches if pressure is marginal.
4) When to call roadside assistance in California
Calling roadside assistance early can reduce risk and prevent costly secondary damage. With a car hire vehicle, that matters because wheel rim damage, underbody scrapes, and towing from unsafe locations can be chargeable if caused by continued driving on a flat.
Call roadside assistance if:
1) The tyre is flat to the rim, shredded, or has a visible sidewall cut.
2) You see a bulge, split, or cords showing, which indicates structural failure.
3) The kit is missing, damaged, or the sealant is expired.
4) The tyre will not hold air after using the kit, or drops pressure quickly.
5) You are in an unsafe location, on a narrow shoulder, or in heavy traffic.
6) The wheel rim looks bent, cracked, or gouged, often from driving on low pressure.
7) A warning appears that suggests other issues, such as brake, stability, or suspension faults.
As you wait, move to a safe spot with barriers if possible, keep hazard lights on, and stay clear of traffic. If you need to communicate location, use mile markers, nearby exits, or your phone map pin. Keep your rental agreement details accessible.
If your trip begins at San Francisco and you chose a larger vehicle, you may be comparing options like SUV rental San Francisco SFO. SUVs can still be supplied without a spare, so it is worth checking the boot at pickup for the mobility kit and reading the instructions before you leave the car park.
5) How to avoid damage and towing charges
The most expensive mistake is driving too far on a deflated tyre. Even a short distance can destroy the sidewall and grind the tyre off the rim, damaging the alloy wheel. That can turn a simple puncture into a wheel replacement, and it also increases the chance you will need a tow.
Do not do these things:
Keep driving at freeway speeds after the warning light comes on. Ignore a pulling sensation. Continue after hearing flapping or rhythmic thumping. Attempt to limp to a distant destination on a flat tyre.
Do these instead:
Stop as soon as it is safe. If you must move, drive at walking pace only to reach a safer shoulder or parking area, and stop immediately. Use the kit only if it is appropriate. If not, call roadside assistance early.
Be cautious with potholes and kerbs after a repair. A sealant fix can be sensitive to impact. Hitting a pothole can reopen the puncture or crack a rim, and the result may look like sudden failure even if the original puncture was minor.
Keep receipts and notes. If you pay for air, a tyre inspection, or a repair recommended by the rental provider, keep documentation. If you are told not to repair and to wait for assistance, note the time and the name of the person you spoke to.
Refuel and return planning. If you are heading to an airport return, build in time. A slow leak can worsen in traffic or heat. For example, if your return is in the Los Angeles area and you used a mobility kit, allow extra buffer before reaching car rental Los Angeles LAX so you can stop and re-check pressure if needed.
6) Picking up your rental, quick checks that prevent trouble later
A little preparation at pickup reduces stress if a puncture happens.
Check the boot for the kit. Confirm you have a compressor and sealant, and that the hose connections look intact. If the car has run-flat tyres, there may be no sealant, so ask where the instructions are and what the driving limits are.
Confirm tyre condition. Walk around the car and look for low tyres, uneven wear, or sidewall scuffs. Report anything obvious immediately so it is recorded.
Know where the tyre pressure label is. It is usually on the driver door jamb. That number is what you should inflate to when using the kit, not the maximum shown on the tyre sidewall.
Save local pickup details. If you are collecting in San Jose and want a reference point for local services and timing, keep a note linked to your provider page such as Hertz car hire San Jose SJC. Having the correct location and contact information ready can speed up help when you are on the roadside.
7) After the puncture, what to do before returning the vehicle
If you used sealant, treat the tyre as temporary even if it seems fine. Re-check pressure periodically, especially after temperature changes. California heat can raise pressure readings, and cool coastal evenings can drop them again, which may reveal a slow leak.
Do not attempt to remove the object (nail or screw) unless the kit instructions tell you to. Removing it can enlarge the hole and cause rapid deflation.
When you reach a tyre shop, ask for a professional assessment. Some punctures can be repaired properly, while others require replacement. With a rental, follow the provider guidance on approvals, and keep any written recommendations.
If the car must be towed, ensure the towing is authorised through the correct channel. Unauthorised towing from restricted areas can lead to complications and extra fees, particularly if storage charges accrue.
FAQ
Can I use the sealant kit on a sidewall puncture? No. Sealant kits are intended for small tread punctures. Sidewall damage is structural and unsafe, so call roadside assistance.
How far can I drive after using a tyre mobility kit? Treat it as a short, temporary solution to reach a safe location or tyre service. Keep speeds low and re-check pressure after 5 to 10 minutes.
What if the tyre pressure light comes back on shortly after inflation? Stop as soon as it is safe and re-check pressure with the compressor gauge. If it drops again, do not continue driving, arrange roadside help.
Will driving on a flat tyre increase charges on a car hire? It can. Driving on low pressure can damage the tyre and wheel rim, turning a puncture into a larger repair. Stopping early helps avoid secondary damage.
Should I tell the tyre shop that sealant was used? Yes. Sealant can affect how the tyre is repaired and may require extra cleaning. Informing them avoids delays and ensures a proper inspection.
