Tyre manufacturing has changed a lot over the years, but how does that affect scrubbing in new tyres? Let’s find out…
Ask many riders how many miles it takes to break in new motorcycle tyres and they’ll tell you that the release agents used in the moulds during manufacturing mean it can take a good 100 miles, with those first few dozen needing to be taken very, very carefully.
Bike rubber did come with a slick coating of slippery goo in the past, which meant scrubbing them in took some very cautious riding after picking it up from the tyre fitter. But in 2023, how has that changed?
How to scrub in motorcycle tyres
Tyre manufacturing has advanced over the past few years, and it’s only one or two that still warn about release agent – see the quotes below from the leading manufacturers. But you still need to be careful.
On track a good rider will scrub in a new pair of tyres very quickly, but on the road you should be careful for 50 to 100 miles. But it depends…
Don’t wind the throttle on hard, and look well ahead to avoid sharp braking. Even when you’re upright leaving the tyre fitters, just wind it on gently.
Then all you need to do is progressively use the unworn areas of the tyre by leaning a little more each time. That means the first corner you enter might have a very small amount of lean, then the next a little more, the next more still and so on; each corner (and don’t forget you need to do the same for lefts and rights) will see you using a little more tread that’s new, while overlapping with some you’ve already covered.
Don’t wind on the throttle too hard coming out of those bends, and do still be careful with your braking.
Leaning a little more in each corner allows the worn-in contact patch to gradually move around the tyre
But without release agents being used on most tyres anymore, why do you need to scrub them in at all? For a start, you shouldn’t underestimate how different the fresh new rubber will handle compared to something that’s heavily worn, so give yourself a chance to get a feel for it.
Add to that what Tony Charlton, Technical manager at Michelin tells us; “The vulcanisation and cooling process of every tyre still causes oils and waxes within the rubber compounds to raise to the surface and form a sheen. This can be very slippery and take a number of miles to wear off, even where non-stick tyre moulds have been used without a mould release agent.”
The answer to how many miles you need to ride to scrub in new tyres is that it depends on how you ride and what the roads are like. If you’re barely leaning over on a cold, wet motorway it’ll take a lot longer than if you’re on a warm, dry, twisting back-road. The point is that motorcycle tyres need to be progressively worn in across their surface. So don’t ride 50 miles motorway, then try to get your knee down at the first roundabout.
Motorcycle tyre manufactures will of course have to give a very cautious statement to avoid any potential litigation, but by listening to what they all have to say really will give you the confidence to enjoy your new rubber…
Using the correct tyre pressures is always vital
What the manufacturers say about scrubbing in new tyres
Before explaining how modern motorcycle tyres need scrubbing in, we asked some of the world’s leading brands for the official advice. Here’s what they said when we asked them in January 2023:
Avon: “When new motorcycle tyres are fitted, they should not be subjected to maximum power until a reasonable 'running in' distance of 100 dry miles (160km) has been covered as a minimum. Tyres should then be visually examined and their inflation pressure re-checked before riding. In terms of how to scrub them in, sweeping A and B roads are prime territory, avoiding motorways.”
Bridgestone: “Use care when riding on new tyres. We recommend that you ride slowly and carefully for the first 60miles / 100km until you become accustomed to the performance of your new tyres in conjunction with your motorcycle. We recommend avoiding extreme manoeuvres, including sudden acceleration, maximum braking and hard cornering, until you become accustomed to the performance of your tyres in conjunction with your motorcycle.”
Continental: “New tyres have a smooth surface after the production process, which gets abraded only through the moderate breaking-in of the tyres. Sudden braking and acceleration, and hard cornering should be avoided until the breaking-in process has been completed. Only after the surface of the tyre is sufficiently abraded is it able to build up its maximum grip level. Continental’s premium tyres (SportAttack 4, RoadAttack 4, RoadAttack 3, TrailAttack 3 and TKC70) use ‘Traction Skin’, a revolutionary micro-rough tread surface that virtually puts an end to tyre break-in. This is achieved with a new mould coating technology that eliminates the need for any tyre release agents.”
Dunlop: “Replacements for worn, differently patterned or constructed tyres will not react the same. When you get new tyres fitted, do not subject them to maximum power, abrupt lean-over or hard cornering until you’ve covered a reasonable run-in distance of approximately 100 miles. This allows you to get used to the feel of the new tyres or tyre combination, find the edge and achieve optimum road grip for a range of speeds, acceleration and handling uses. Check and adjust the pressure to recommended levels after tyres cool for at least three hours following run-in. Remember, new tyres will have a very different contact patch and lean-over edge. Mixing a new tyre with a worn tyre and mixing different pattern combinations may adversely affect the ride and handling and will require careful ride evaluation.”
Maxxis: “We recommend that riders take care at first, in order to remove any mould-release agent that might remain on a new tyre. It’s important to avoid hard acceleration and high lean angles.”
Michelin: “On the road, new tyres require a period of bedding-in before normal use. Michelin suggests that riders start slowly and use gentle acceleration and braking and low lean angles to bed the tyres in, gradually increasing the demands on the tyres until you become accustomed to the performance of your new tyres in conjunction with your motorcycle and to fully scrub off that ‘new tyre’ look before subjecting the tyres to normal use. Michelin recommends at least 60 miles / 100 kms for this process. This applies to all our motorcycle and scooter tyres.
Pirelli/Metzeler: “In order for your new tyres to provide optimum performance, they should be ridden on very cautiously for the first 100-200 kms. Immediately after new tyres are mounted, sudden acceleration, heavy braking, and hard cornering must be avoided until the 100-200 kms run-in period is completed.”
Bonus info for tyre swots
Want to impress your mates with tyre knowledge? Here are some useful nuggets of information…
- You can ‘over-tyre’ a bike. Track-focussed tyres that you might consider ‘super sticky’ are intended to work best at high temperatures, so if they’re used on the road and don’t keep that temperature up, they might not perform as well as rubber that’s designed for the road. Yes, even if you consider yourself a fast road rider.
In all honesty, modern sport-touring tyres are the best option for pretty well anyone now. Don’t believe us? Have a look at what the instructors are using next time you ride one of the discounted Bennetts BikeSocial track days.
- The best tyre pressure is the one the bike manufacturer tells you. For road riding, use the pressures stated by the bike or tyre manufacturer and check them when they’re COLD, not after a ride. On the majority of motorcycles that’s 36psi at the front and 42psi at the rear, but always check.
Tyre pressures are not arbitrary – they’re worked out based on the loads on the tyres by the European Tyre and Rim Technical Organisation (ETRTO). Even on track, if you’re new to riding on a circuit just leave your tyres at the standard pressures and concentrate on enjoying yourself.
- Do NOT drop tyre pressures in the cold and/or wet. Tyre tread patterns are designed to work at a specific pressure, so don’t let your tyres down in the wet as the tread grooves will close up and become less efficient. It’s also not true that you’ll increase the contact patch as the tyre can tend to bow in the middle, when underinflated, rather than spread out flat as some might expect.
Don’t listen to people who claim dropping pressures in the wet is a good idea. It’s not.
- Only when you’re getting fast on track should you drop pressures. If you’re noticing the edges of your tyres ‘balling up’, this is usually just the worn rubber sloughing off as the tyre wears. The high temperatures generated on track mean that the micro particles of worn and discarded rubber adhere to the tyre, rather than dropping away as they would on the road. They’re then pushed to the edge of the tyre during cornering, forming balls of rubber on the tyre edges.
If the rubber building up on the edge appears more of a shiny, molten smear than small balls, this is called ‘hot tear’ – an indication that the tyre is over-inflated, typically due to the pressure not having been reduced for fast track use. As the temperature inside the tyre increases, so does the pressure, and this over-inflation can lead to a smaller contact patch. Dropping the pressure a little will bring the contact patch back to its designed size and shape, thus spreading the load and forces, so helping to control heat generation.
If you’re seeing smearing of the rubber on your tyre – usually once you get into the intermediate or fast groups on a track day – you should start dropping pressures, but it’ll vary by the type of tyre and your riding style. To get started, you could check the pressures as soon as you get in from the first session of a track day (while they’re still hot) and just reduce them to 36psi at the front and 42psi at the rear. But make sure you pump the tyres back up before riding home, checking them again when they’re cold.
- Cold tear occurs when tyres used on track aren’t getting warm enough. The surface of the tyre generates heat during use, with rubber sloughing away through normal wear, but if the internal carcass rubber is significantly cooler, it resists that pulling away and causes the surface rubber to tear instead.
Increasing the tyre’s pressure raises the temperature during use as the same load and forces act on a slightly smaller contact patch size; this more worked tread rubber transmits its heat to the whole tyre more effectively.
- Don’t mess around with sizes. It’s important that you fit tyres that are the right size, and that meet the load and speed requirements of your motorbike. There’ll be a specific axle weight at the front and rear, so based on the specifications set out by the ETRTO, the leading tyre manufacturers will be able to recommend rubber that suits your bike and your riding style; most should have a tyre selector on the website.
- Different engines cause different wear. The pulses from a big twin engine can put a greater load on motorcycle tyres. As you accelerate, the rubber is squeezed against the road, and if that comes in pulses, it can cause increased heat and wear compared to a smoother inline-four.with traction control, the squeeze will be pulsed, causing increased heat and wear.
- Spinning up the rear isn’t the only way to wear out tyres. In the same way as a big V-twin can wear tyres more quickly, the pulsing caused by traction control when it intervenes to prevent the tyre spinning can also cause more heat and wear.
Don’t scrimp on replacing the valve
- Rubber tyre valves must be changed with the tyre. Make sure your tyre fitter replaces any rubber tyre valves as they can perish and cause a flat.
- Chicken strips don’t matter. “Many riders never explore the high lean angles that modern high-performance tyres are capable of achieving,” said Tony Charlton from Michelin, “and it’s normal for some of the tread area to remain completely unused. The presence of any unused tread at the shoulder extremities is not an indicator that faster or tighter cornering is possible; the forces generated at high lean angles and speeds place increased demands on tyres and maximum grip is finite, and only available in perfect conditions.”
Ultimately, what matters is that YOU enjoy riding YOUR motorbike. Nobody that matters will ever judge you on that…
