New Tyre Slippage

  1. My model of MX-5 is: NA
  2. I’m based near North Chingford

Just purchased 4 new Vredestein Sportrac 5 tyres. After having them fitted I picked up a friend and on the way home lost traction of the front of the car on a roundabout, albeit I did drive spiritedly but nothing too silly.

When I got home I checked all the tyres, they are on 34 psi and I have learnt that some/all tyres need a breaking in period. What should this be?

This isn’t especially important on motorbike tyres. Usually manufacturers recommend 5-600 miles of gentle use to break them in.

For a car they’re heavier but also probably have harder compounds ton compensate so can’t see that being too far away

  1. Deflate to 26 PSI (as handbook!) immediately and keep them there from “cold”.
    34 PSI is grossly OTT bordering on bl**dy suicidal in wet or greasy stuff.

  2. Many new tyres have traces of “release fluid” from the factory which needs buffed out over 50/ 100 miles max.

  3. The person who blew yours up to 34 PSI and sent you on your merry way needs spoken with followed by a ruddy good slap around the ear 'ole so they don’t forget. ( Unless they are bigger than you and holding a tyre wrench)


Tyres are now at 26 psi

Will take it for a drive and not a spin later…:wink:


Consider yourself forgiven
Happy miles & smiles. :grinning:

All of the above, spot on.

I’d be amazed if the OP doesn’t find the tyres good. I had Sportrac 3 on a Mk2 and they had tons of grip. At 26psi.

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It is not the pressures but the newness. You have not even taken the whiskers off them yet. Even Lewis Hamilton is expected to take a couple of corners to get the tyres fully in the groove even though they have come out of tyre blankets at 80 C.
The 26psi is something chosen by Mazda to give an all round blend of comfort and compliance, it is not a holly grail pressure. Lots of the MX-5 race cars will use 40 plus to stop the tyre rolling on the shoulder. The basic principal is more air stiffens the tyre and so the tread takes more load and generates more heat, the less pressure and the sidewalls flex more and generate more sidewall carcase heat. It is a balancing act, but 34psi is not lethal, it will just make you feel the bumps a bit more and the tyre response will be sharper.

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Thanks Nick…every day is a school day.

I was surprised to see the whiskers like that on the car tyre. Will take it easy for the next 50 or so miles.

So basically psi from 26 to 32 shouldn’t be the end of the world. Will see how it goes from 26 psi then maybe experiment a little.

Thank you all for your comments.

Well, from my professional experience, life experience and indeed what Michelin taught me, overinflated tyres are not a good idea.

For example, if tyre pressures are too high, then less of the tyre touches the ground. Because it will distaught the design profile of the tyre. The outer and inner parts will be less in contact with the road and therefore the centre of the tyre will wear more rapidly.
If too under inflated the opposite effect will take place.
Indeed, seriously under inflation is the worst because more heat builds up and serious delamination can take place with obvious consequences.

Too high pressures will also make the ride very hard and skittish (as SF states above).
As a result, not only will your tyres wear prematurely, but the handling and driving experience will be horrible.

Car manufacturers work “very” closely with the tyre industry to make sure a tyre is up to the job with the correct recommended pressures taking into account weight of the car with low loads and higher loads. It’s done for safety, comfort, handling and good even wear of the tyres.

As above around 100 miles will see the tyres bed in and will get better with a few more miles on.

Lots of race cars and indeed motorcycle racing actually have very low pressures to give them more grip (and indeed create heat for the compound design) to push the tyres into the road/track surface, (the contact patch). How many times have we read that the driver/rider has been penalised for running under inflated tyres as recommended by the rules……Of course race tyres are a different subject really in there own right.

Just my opinion on matters of course. :slightly_smiling_face::+1:


Not important on motorbikes? You’re joking of course? Many motorcyclists have been up the road because of not riding carefully on new tyres, I know several (me included, ended up in A&E)
New tyres do need to be run in and they will still be covered in mould release agent which needs to be slippery.


This response is not about being argumentative but about countering the common internet belief, across most subjects, that there is only one possible right way.
34psi is not over inflated as far as the tyre goes. It is over the Mazda recommended settings of 26PSI designated as a world wide setting, from the heat of California to the cold of Finland for tyres that do not even exist any more. Tyre pressures vary in use and even if the sun is on the tyre, constantly and the very important point I am making is 26psi is not a magic pressure where everything is perfect. Did Mazda even change the 26PSI recommendation across the variants of car who’s weight varied significantly? It is not a Holly Grail pressure when everything is right and it varies in use continually.
Radial tyres are very good at keeping their cross sectional profile and 34 PSI is well within the acceptable limits for a tyre and very much a pressure that will be common on that tyre on certain vehicles.
Race cars do not inherently run very low pressures to give more grip. Starting pressures may well be lower as the energy and therefore heat that is put into the tyre will increase pressure to where they want it to be. However plenty of drivers have ruined their tyres before they have even come to temperature by fatiguing the sidewalls or running curbs before having sufficient pressure to support the tyre. I had one happen just Saturday which cost the driver a £200 tyre in just one lap. And of course one of the most famous incidents in recent times is Ayrton Senna’s death, attributed to loss of tyre pressure behind the slow safety car allowing the car to bottom out.
This Car won the 24 Rockingham C1 race with 50PSI Cold pressure in the front and 70PSI in the rear.
Different car and different day, but this guy used the manufacturer recommended pressures.
The point is, things can be different and not wrong.

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you’re thinking of this! Always amazes me how these ever stay on the rims,

Nick, ever supplied rear tyres for a dragster?

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Might have

They stay on the rims Martin because they are clamped. See those screws on the outer rim. It deforms because they don’t want wheel spin and the tyre grows in diameter as it goes down the strip. Not very good at going sideways though !

Top Fuel Dragsters are a whole other world. I love this video of the fuel injection for just one cylinder.

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I won’t copy your message as it’s already there. :+1:
Looks like the topic has been resolved anyway, but to answer your post.

You will see that I was very “Careful” not to get into the realms of stating actual tyre pressures for the MX5, or indeed any other car.
I was also very careful not to quote or copy what you (or indeed any one else) has stated, as we probably all have a slightly different opinion, (as you say) on matters.
Likewise, I was not getting into an argument as indeed that is really pointless and unnecessary, merely giving my opinion.
Forums are designed exactly for this purpose to debate and indeed give opinions whether we agree with them or not as everyone is entitled to one.
The odd PSI’s here and there will “probably” make no real difference.
What people actually do is indeed a matter for them.

As you will know tyre pressures are set at cold/non use for a reason as when the car gets driven the tyres heat up, (friction) the air expands (if indeed air is used see below) and the pressures rise to the optimum pressure for the car as set by the manufactures.
These “hot” pressures will vary depending on the actual structure of the carcass and the materials used to construct it.
It matters not whether the vehicle is in Finland or California, the actual principles will be the same.

I was merely stating what is common knowledge across the board regarding road tyres including cars, caravans, motor homes, HGV’s or whatever regarding serious over inflation and indeed serious under inflation. HGV tyres “Tend” to shred because they over heat due to low tyre pressures perhaps as a result of a slow puncture as just one example.

Likewise, as you say getting into a debate about what race cars actually run is a mine field and perhaps again pointless as it depends on the type of racing.
As an example, F1 use Nitrogen in the tyres too as this maintains stable PSI and temperature throughout the “race conditions” for many reasons.
Currently, Pirelli instruct the F1 teams to run minimum pressures. Again, as an example, 21PSI Front and 21PSI Rear for the 2021 French GP, so much much lower than the racing you have mentioned.

F1 pressures are imposed to limit the grip of the tyre and the stresses imposed upon its structure, (for obvious reasons). Running below that will increase the contact patch of the tyre, (as I stated before) ie there will be more rubber on the road and therefore more available grip.
BUT “may have” negative points in other areas (remember we are talking race tyres here).
If motorcycle racers had too high pressures the contact patch would be decreased and 9 times out of 10 they would crash.

It’s just impossible to compare across the board.
Anyway, that’s enough really thanks for the input and all the best. :+1: :slightly_smiling_face:

Well, not quite! :joy:
A cracking example though. :+1:

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I am sorry, but nitrogen is used because bottled Nitrogen, which is what is used is “dry”. meaning no moisture. It is possible to used dry air but the equipment required means bottles are far easier. “Air” which is 4/5th Nitrogen anyway and “Nitrogen” all follow the gas laws. It is the potential moisture from compressing atmospheric air that is the issue. Then you start getting into dew points end everything else. When race tyres are run so hot, then moisture boiling is an issue, it is not that the gas is more stable. I have known issues with tyres that seem to defy logic till it was worked out the the moisture within the tyre actually came from the bead paste used to mount them.
The stipulation from Pirelli about minimum pressures comes from the requirement to use the tyre as most of the suspension movement and so pressures become very important in fine tuning the balance of the car, which is true in any car. Lower pressures also result in more drag, which as most F1 overtaking takes place in a straight line, then the balance matters. The tuning of that balance and getting compliance in the tyre to make the car work better was resulting in lower pressures at certain circuits that were stressing the sidewalls and causing failures, it was not about general grip. :innocent:

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I sometimes think that you over think matters and don’t really read what I have written properly, even though again you have quoted what I said in your reply.

No where have I mentioned moisture, the science behind why “dry nitrogen gas” is used, only that it “is” used for stable temperatures and PSI and for many reasons. I know exactly “why” but wont go into on here.
As said before a completely different topic than this thread.

Let’s be correct.
The atmosphere is “basically” made up of let’s call it 78% nitrogen and 21% oxygen, (moisture in this case) and other gases. Yes I googled that aspect like you. By removing the oxygen gives you the dry nitrogen, i.e. no moisture and then has to be bottled for various uses for very obvious reasons.

Likewise, I do not completely agree with your latter comments. But that’s your opinion which I respect.
As I said, “BUT may have negative points in other areas”.

Pirelli instructed the teams to increase pressures at “some” circuits because of safety due to failures/potential failures. But the drivers would actually want lower pressures specifically for the nature of the F1 car.

Perhaps time to agree to disagree and move on. (Well I am anyway). Enjoy your evening. :slightly_smiling_face::+1:

I read that as a typo