Every car owner who stores a vehicle for more than a few weeks faces the same invisible problem: flat spots.
You park the car. It looks fine. Weeks or months later you drive away, and the first kilometre feels wrong — a rhythmic vibration, a shimmy through the steering wheel, a thud with every rotation. That is a flat spot. And the climate, where cars sit for entire summers, it happens faster than most people expect.
This guide explains what flat spots are, why they form, which cars are most at risk, and the only reliable way to prevent them entirely.
What Is a Tyre Flat Spot?
A tyre flat spot is a localised deformation of the tyre's rubber where it contacts the ground during storage. When a car sits stationary, its full weight — typically between 1,200 kg and 3,500 kg — presses down on four contact patches, each roughly the size of a human hand.
Over time, the rubber in those patches compresses. The sidewall stiffens. The circular profile of the tyre deforms slightly into a flatter shape at the bottom. When you drive again, that flat section rotates through each cycle, creating the vibration you feel.
There are two types of flat spots:
Temporary flat spots form during short storage periods — usually under four weeks. The rubber is still elastic enough to recover once the tyre warms up through driving. They typically resolve themselves within 10 to 15 kilometres.
Permanent flat spots form after extended storage, especially in heat. The rubber undergoes a chemical change that prevents full recovery. These do not fix themselves with driving. The tyre must be replaced.
Why climate Makes This Worse
Tyre rubber is a temperature-sensitive material. Heat accelerates every process that causes flat spots:
- At 40°C+ the rubber compound becomes more pliable under load, meaning deformation happens faster and sets more deeply
- UV radiation degrades the anti-ozone chemicals in the rubber, reducing its elasticity and recovery ability
- Extreme temperature swings between day and night create repeated expansion and contraction cycles that stress the sidewall
A car stored in a garage during summer can develop a flat spot in as little as two to three weeks. The same car stored in a climate-controlled garage might take three months to show the same damage.
Which Cars Are Most At Risk?
All cars with pneumatic tyres are susceptible, but some are significantly more vulnerable:
High-performance and sports cars carry more weight per tyre due to wider, lower-profile tyres with stiffer sidewalls. A 235/35 R19 tyre has far less sidewall to absorb load than a 205/55 R16.
Supercars and hypercars often use ultra-low-profile performance tyres that were never designed for extended static load. Michelin Pilot Sport Cup 2 and Pirelli P Zero Trofeo R tyres — common on Porsche, Ferrari, and Lamborghini — are especially vulnerable.
Heavier vehicles exert more force on each contact patch. An SUV or large saloon at 2,500 kg distributes more load than a compact at 1,400 kg, causing faster deformation.
Collector cars stored seasonally are the highest-risk category — often expensive, often on specialist tyres, often stored for months at a time.
Methods That Do Not Work
Several common approaches are widely recommended but have significant limitations:
Moving the car every few days — Works only if done consistently every two to three days without exception. Impractical for most storage situations and impossible for remote or long-term storage.
Over-inflating the tyres — Increases the internal pressure that resists deformation, but creates its own risks: uneven wear on return to use, reduced grip, and potential structural stress on aged sidewalls.
Tyre supports that only contact the tread — These exist on the market and address part of the problem, but miss the most critical factor: the sidewall.
The Only Method That Fully Prevents Flat Spots
The only reliable, zero-maintenance solution is to remove the static load from the tyre entirely — or redistribute it across a far larger surface area.
Removing the load entirely means using axle stands to lift the car off the ground. This works perfectly but requires mechanical access, appropriate stands for your vehicle's jacking points, and willingness to work under the car. It is not practical for most owners.
Tyre cushions redistribute the load without lifting the car. A correctly engineered tyre cushion increases the contact surface area between the tyre and the ground by up to 400%, dramatically reducing the pressure-per-square-centimetre on any single point of the rubber.
The key word is correctly engineered. A flat piece of foam under the tyre does almost nothing — it marginally increases surface area but does not cradle the sidewall, which is where the most damaging deformation occurs.
The ALTairEGO cushion uses a concave profile that supports both the tread and the lower sidewall simultaneously. This is the critical difference. When the sidewall is supported, it cannot deform inward under load. Flat spot formation stops.
How to Choose the Right Tyre Cushion for Your Car
Tyre cushions are rated by maximum kerb weight — the total weight of the car including fluids but not passengers or cargo. You can find your car's kerb weight in the owner's manual, the door sill sticker, or the manufacturer's website.
- ALTairEGO Super — up to 2,000 kg. Suits most sports cars, performance saloons, and compact SUVs.
- ALTairEGO Magna — up to 2,750 kg. Suits mid-size SUVs, large saloons, and GT cars.
- ALTairEGO Leader — up to 4,000 kg. Suits large SUVs, commercial vehicles, and heavy performance cars.
Using a cushion rated below your car's kerb weight will not provide full protection. When in doubt, size up.
Step-By-Step: How to Use Tyre Cushions
- Place one cushion on the ground in front of each tyre, curved side facing up
- Drive slowly forward until each tyre is fully seated in the cushion
- Apply the handbrake and leave the car in gear or Park
- The cushion will hold the tyre in the correct supported position for the duration of storage
- When ready to use the car again, simply reverse off
The entire process takes under two minutes. No tools, no lifting, no mechanical knowledge required.
Storage Checklist Conditions
Before leaving a car in storage, complete the following:
- Tyre pressure — inflate to the upper end of the manufacturer's recommended range (not beyond the maximum printed on the sidewall)
- Tyre cushions — place under all four wheels before parking
- Battery — connect a maintenance charger such as a CTEK to prevent discharge
- Car cover — use a breathable cover to prevent dust damage and UV degradation of paint and rubber
- Handbrake — apply, but note that on very long storage (over six months) the brake pads can bond to the discs; leave in gear instead if storing beyond this
- Coolant and fluids — check levels before storage, not after
Frequently Asked Questions
How long does it take for a flat spot to become permanent? In summer conditions, permanent flat spots can form in as little as four to six weeks on performance tyres. On standard passenger tyres, the threshold is typically eight to twelve weeks. Prevention is always more reliable than waiting to see.
Can I use tyre cushions on any car? Yes, provided you select the correct weight rating. The ALTairEGO range covers vehicles from 0 to 4,000 kg kerb weight.
Do tyre cushions work on low-profile tyres? Yes. The ALTairEGO concave profile is designed to support tyres from 185 mm to 400 mm wide, including ultra-low-profile performance tyres commonly found on sports cars and supercars.
Will driving on a flat spot damage the tyre permanently? A temporary flat spot that has not set will resolve itself within a few kilometres of gentle driving. A permanent flat spot will not resolve and may cause handling instability that makes the car dangerous to drive. If vibration persists after 20 kilometres of driving, have the tyres inspected before continuing.
Are tyre cushions reusable? ALTairEGO cushions are made from high-density recycled rubber and carry a lifetime guarantee. They do not degrade under repeated use or prolonged load.
ALTairEGO tyre cushions are available in three lines — Super, Magna, and Leader — covering all vehicles up to 4,000 kg kerb weight.