Tyre flat spots are one of the three things every owner asks about before a car goes into storage, alongside the battery and the brakes.
The honest answer is that most of them roll out and some of them never do, and which one you get is decided by five things you can mostly control.
Here is what is actually happening in the tyre, and what to do about it.
What Tyre Flat Spots Actually Are
A tyre standing still carries the weight of the car through one small patch of rubber. That patch is held deformed for as long as the car does not move.
Two things then happen. The rubber compound takes a temporary set, which relaxes once the tyre warms and flexes again. The carcass underneath, the belts and plies, can also take a set, and that one does not relax.
The first is a vibration for the first few miles. The second is a permanent vibration and a scrapped tyre. Telling them apart on day one is impossible, which is why prevention is the whole strategy.
The Five Things That Decide It
- Temperature. Cold rubber is stiffer and takes a set faster. A tyre that goes into a cold building warm, then cools under load, is the worst case.
- Time. Days are nothing. A few weeks usually rolls out. Beyond about three months the odds start moving against you, and beyond a year they are poor.
- Pressure. An under-inflated tyre has a bigger, deeper contact patch. This is the single easiest thing to fix and the most commonly ignored.
- Construction. Low-profile, stiff-sidewalled and performance tyres take a set more readily than tall, soft touring tyres. Competition rubber is worse again.
- Age. Older rubber has already hardened, so it holds a deformation rather than recovering from it. A five-year-old tyre behaves very differently from a new one.
Raised Pressures Are the Cheap Fix
Inflating above the normal running figure is the standard preventative and it works, because it shrinks and shallows the contact patch.
Raising to somewhere around the tyre’s maximum sidewall pressure is the usual approach for a long stay, and that figure is moulded into the sidewall rather than printed in the handbook.
What is not useful is the eighty psi folklore. Far beyond the sidewall maximum the tyre distorts in a different direction and the carcass suffers, so the number on the tyre is the number to respect.
Raising pressures is step five of our eight-stage intake, and dropping them back to running figures happens before collection rather than after.
Better Than Raised Pressures
Taking the weight off the tyre entirely removes the problem rather than reducing it. For a car staying a year or more, or any car on competition rubber, this is the right answer.
Axle stands under proper jacking points, or a set of purpose-made supports, let the suspension hang and the tyres carry nothing. It also spares the springs and dampers sitting compressed for months.
Moving the car a few feet every month or two is the middle option. It shifts the contact patch to fresh rubber, which is better than nothing and worse than stands.
The Thing Nobody Mentions: Age
A tyre ages on a calendar, not a mileage counter. Compound hardens, sidewalls develop fine cracking, and the rubber loses the flexibility that lets a set relax out.
Every tyre carries a four digit date code on the sidewall: the week and the year it was made. A set that was five years old going into a three-year stay comes out at eight, and eight-year-old tyres are a replacement conversation regardless of tread depth.
We record date codes at intake for exactly that reason. TyreSafe is a useful independent source on reading them and on ageing generally.
What to Do on Collection Day
Pressures back to running figures before the car moves, not after the first junction. Then drive gently for the first few miles and let the tyres warm through.
A temporary set usually disappears within five to ten miles. If a vibration is still there at twenty miles, it is not going to clear, and the tyres need looking at properly.
Check the sidewalls while you are there. A tyre that has sat flat-spotted and hardened sometimes shows cracking that was not visible before the stay.
What It Costs
Raising pressures costs nothing and is included in the intake. Secure indoor storage is £150 a month including VAT for the first three months, then £165, and the humidity-controlled bay is £200, then £225.
A set of tyres on a performance car is several hundred pounds and on a supercar considerably more, which is why the free step is the one worth getting right. Figures sit on the locations and pricing page.
How Pitstop 66 Can Help
Every car gets its pressures raised on arrival and its tyre date codes recorded, and every car gets a visual check every working day, which is how a slow puncture gets caught in a week rather than a season.
For long stays we can put the car on stands, and mechanics are on site if tyres need replacing before collection. Detail sits on the professional car storage page and long-term car storage.
Owners reach us from Stockport and Trafford. To arrange storage that takes tyre flat spots seriously, enquire here or call 0161 464 7494.
Also worth reading: storing a track car between seasons, what changes after the first twelve months and why brakes seize after a lay-up.
Key Takeaways
- Compound sets relax out. Carcass sets do not, and you cannot tell which you have on day one.
- Temperature, time, pressure, construction and age decide the outcome.
- Raise pressures towards the sidewall maximum. Ignore the eighty psi folklore.
- For a year or more, or on competition rubber, take the weight off with stands.
- Read the date codes. Tyres age whether or not they turn.
Do tyre flat spots always go away?
No. A temporary set in the compound relaxes once the tyre warms, usually within five to ten miles. A set in the carcass is permanent, and the tyre has to be replaced.
How long before flat spots become permanent?
Days are nothing and a few weeks generally rolls out. Beyond about three months the risk climbs, and beyond a year on a cold, under-inflated, older tyre it is likely.
What pressure should I store a car at?
Towards the maximum pressure moulded into the tyre sidewall rather than the placard figure in the door shut. Going far beyond the sidewall maximum does more harm than good.
Is it better to put the car on stands?
For a long stay, yes. Taking the weight off removes the problem rather than reducing it, and it spares the springs and dampers sitting compressed as well.
Does moving the car occasionally help?
It shifts the contact patch to fresh rubber, which is better than nothing. It is a middle option rather than a solution, and short engine runs bring their own problems.
Do you record tyre condition?
Yes. Tread and the four digit date code on each tyre are noted at intake, so nobody is surprised by ageing rubber at collection or at sale.
