The 85% Rule – Myth, Guide, or Outdated Advice?

If you’ve spent any time researching caravan towing, you’ve almost certainly heard this:

“You should stick to 85%.”

It’s often presented as a hard rule.
Sometimes as a warning.
Occasionally as something you’re judged by.

But what is the 85% rule — and does it still deserve the attention it gets?

Let’s calmly unpack it.

What the 85% rule actually says

In simple terms, the 85% guideline suggests:

The caravan’s MTPLM should be no more than 85% of the car’s kerbweight.

That’s it.

It’s not law.
It’s not a safety system.
And it’s not something your car “knows” you’re following.

It was introduced as a confidence guideline, not a legal requirement.

Where the 85% rule came from

The guideline originated decades ago, when:

  • Cars were generally lighter

  • Engine power was lower

  • Stability systems didn’t exist

  • Caravan suspension and chassis design were less advanced

At the time, it was a simple, conservative way to help less experienced drivers avoid pairing very heavy caravans with relatively light cars.

In that context, it made sense.

Why it stuck around

The 85% rule survived because it’s:

  • Easy to repeat

  • Easy to remember

  • Easy to present as “safe advice”

Unfortunately, it’s also easy to misunderstand.

Over time, it became:

  • Quoted as law (it isn’t)

  • Used as a pass/fail test (it isn’t)

  • A source of unnecessary anxiety

What the 85% rule is good for

Used properly, the 85% guideline can still be helpful.

It works well as:

  • A confidence-building starting point

  • A way to compare potential tow car / caravan pairings

  • A reminder that towing comfort matters, not just legality

For newer towers especially, it can encourage:

  • Gentler handling

  • Better margins

  • A calmer learning curve

And that’s no bad thing.

Where the 85% rule falls down

The problem comes when it’s treated as absolute truth.

It doesn’t account for:

  • Modern car stability systems

  • Wheelbase length

  • Torque delivery

  • Suspension design

  • Actual caravan loading

  • Driver experience

Two outfits at the same percentage can feel completely different on the road.

The rule also ignores one crucial thing:

👉 How the caravan is loaded often matters more than the percentage itself.

Legal vs comfortable (again)

This is where confusion creeps back in.

You can be:

  • Above 85% and perfectly legal

  • Below 85% and still uncomfortable

  • Exactly on 85% and still poorly set up

The law only cares about legal towing limits.

Your confidence depends on:

  • Loading

  • Nose weight

  • Speed

  • Conditions

  • Experience

The percentage alone doesn’t drive the outfit.

Should you ignore the 85% rule?

No — but you shouldn’t worship it either.

Think of it as:

  • A guide, not a target

  • A starting point, not a judgement

  • One factor among many

If your outfit feels calm, predictable and well within legal limits, the number itself becomes far less important.

A better question to ask yourself

Instead of asking:

“Am I under 85%?”

Ask:

  • Am I legal?

  • Is the caravan loaded sensibly?

  • Does the outfit feel stable at realistic speeds?

  • Do I feel relaxed, or constantly on edge?

Those answers matter far more than a single percentage.

How this fits into Towing Without the Panic

This page exists to remove pressure — not replace one rule with another.

If you arrived here worried about getting something “wrong”, the takeaway is simple:

The 85% rule is a confidence aid, not a towing commandment.

Used calmly, it can help.
Used rigidly, it often causes unnecessary stress.

Where next?

If this page helped, the next useful reads are:

  • Is My Caravan Too Heavy for My Car?
    Understanding legality vs confidence.

  • Caravan Nose Weight Explained (Without the Maths)
    Often more important than percentages.

  • What Actually Causes Snaking?
    Why stability issues happen — and how to avoid them.

All part of Towing Without the Panic.