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3 sisters sprint video with under car view

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Interesting thanks

i was using maxsport 185/55x15 RB5 F3 effectively their super soft. With stiffer sidewalls.

I think I can still run softer at the rear to try and get start and corner exit grip. 

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On the TR3 softer at the rear is probably the direction to go though for short sprints.

However, back to my point about is the deflection of the tyre excessive based on a single data point?

Without wanting to tell my Granny how to suck eggs but the only way to determine the correct tyre presssure for YOUR specific car and setup is to do some proper testing. An actual event is not the time to be doing this unless you already have some information to base your decisions on. Too stressful apart from anything else.

What someone else is running on a different car with a different suspension setup, different engine characteristics, gearbox and final drive ratios, and a different driver on a different track/country can only be the very roughest of rough guides.

So you need to test. On a track that you know well and can get some consistency so differences in the runs are more likely down to tyre pressures that 'other things'. Like spending the time, effort and money on the engine, suspension, etc you now need to do the same with the tyres.

And if you are really keen then testing in the wet is the next step... grim.

Couple of interesting examples which should give you pause for thought before simply adding more air


And away from the rarified atmosphere of F1 to something very much nearer home. This is a Caterham 7. Recomendations for them are generally around 17-19 psi cold. Meant to add that the Caterham is also running a stiffer wheel to tyre width combination for thus level if deflection. You shouldn't try to compensate for a narrower wheel by adding more pressure as this will just lift the centre of the tyre and reduce the contact patch.



Edited by Escadrille Ecosse
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Hello, I realize about all the differences (especially the two pictures above compared to an old Triumph).It was only an observation of our experience which may or may not be of use. The tyres I mentioned are for "racing use only". The picture of the green car (in the discussion) in another thread here, "Members cars and project thread" will show what 27 psi does. Regards, Michael.   

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Hi Michael 

No offence was meant although my comment about different countries was more about the likely significant differences in 'cold' between yourselves and our sepic Isle and needing to know a lot more about your wee green beastie to be able to draw any valid conclusions. 

My point about the two moderns (if you can call a Caterham a modern) was actually the similarities in tyre deflection between the oldies and the state of the art. There is lots. And a couple more comparative data points to the discussion 

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Hello Colin, No offence taken. A selection of variables in the pot might help save a fair bit of heart-ache (then again it might add to it) I think the green car might be "over-tyred" but I'm only the "lackie". There is a bit about it in my rebuild thread. They are similar to people, all different. So an open mind is a pre requisite ? We go from bloo.. to bloo.. cold here too. Regards, Michael. 

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