Tyre Recommendation thread

[aaronng]

I have 34 psi at the moment. I might run more toe out in the future. That should give me knife edge response off centre.

[petsfact]

I think 36 all 4 corner is great for tram road and not too much tires drag on freeway. 38psi is excellent for re001 on freeway but a bit harsh on toorak road.

[aaronng]

Toorak Rd is harsh on everything.

[JohnL]

I have 34 psi at the moment. I might run more toe out in the future. That should give me knife edge response off centre.

Without having any experience of these tyres, this pressure sounds on the low side to me. For 'performance' driving that is, fine for going to the shops!

If the sidewalls are soft then the the tyre will tend to develop large slip angles, which doesn't mean it won't grip well. Imagine gluing your front contact patches to the road, what happens when you turn the steering wheel? The wheel rim will be able to turn a little bit fairly easily before the sidewalls load up in torsion and resistance becomes much greater. The softer the sidewalls the more the rim will be able to be turned to a greater angle relative to the contact patch (even though the contact patch remains in the same place), and the stiffer the sidewalls the less rim angle will be possible. The softer the sidewalls the less precise the steering input will be because steering motion to the contact patch is 'lost' in the sidewall (and to a lesser degree in the tread blocks). Rear tyres can also affect steering response.

A soft sidewall can be 'stiffened' simply by increasing the tyre pressure, resulting in better steering response. This will also increase the tyres vertical 'spring rate', and may 'bulge' the tread (less so with radials than cross ply). Its a compromise and you need to experiment to find what pressure works best overall with a particular tyre on a particular car. We can't consider the car manufacturers reccomended pressures as gospel, they are typically a compromise biased toward soft ride and low NVH, not optimum tyre performance.

I would be cautious of running more than just a tad of toe on a road car. Toe out may increase steering response, but at the cost of tyre wear and possibly causing straight line instability. I doubt toe will be able make up for unstable sidewalls. One thing that will definitely help steering response and on centre feel is increased caster, as much increase as you can make, almost impossible to have too much!

[aaronng]

Well, the car is used for street. No hooning around corners. When on track, it's a different matter as I do increase tyre pressure levels as well as customise them front and rear to improve turn in. I'm wary of running 36 psi on crappy Sydney roads though.

[bennjamin]

you want vauge ? Try RE001's with no PS and increased frontal castor.
Nothing then whooska Still cant complain.

[JohnL]

Well, the car is used for street. No hooning around corners. When on track, it's a different matter as I do increase tyre pressure levels as well as customise them front and rear to improve turn in. I'm wary of running 36 psi on crappy Sydney roads though.

Why is that?

Potential increased danger of puncture? I would think this is very slight.

Handling over bumps? The tyre (itself) may become more 'bouncy', but shouldn't be a problem with appropriate damper setting. I'm running 38 and 45 psi on bumpy roads with no significant adverse handling issues, albeit with a stiff rebound setting. The caveat here is of course that this is with the tyres on my car, other peoples mileage may vary depending on tyres and set up etc. The pressure that works best with a given tyre can vary a lot, as can be seen with the pressures I've ended up with on the two different brands on my car.

This does seem to be related to the tyre, and not what end of the car the tyre is fitted to, i.e. the tyre that works best at 38 works best at that pressure (or very near either side of it) whether that tyre is fitted to the front or rear, and the same for the tyre that works best at 45psi.

With high pressures you may find the suspension becomes 'juddery' (especially on sharp bumps) no matter what damper setting you use, if so then its likely that the upper damper mount rubbers are too soft, as I described in an earlier post.

This is because the tyre is also a spring, and so are the rubber mounts (though they don't 'spring' in the same manner as the tyre or the actual springs because they don't support chassis weight). The tyre has some internal damping, but not much and less so at higher pressure. The damper needs to be on the stiffer side to adequately damp the tyre 'spring'. The damper cannot damp the spring action of the rubber mounts because the rubber is between the chassis and the damper, not between the chassis and the road. All we can do here is to stiffen the rubber mounts to lessen their 'springing' action, which also raises their harmonic frequency possibly taking this out of the range that will cause a problem.

Harshness? Up to you what you can live with. I don't find higher pressures unpleasant on reasonably smooth surfaces, only on broken surfaces like dirt roads or very muchly and poorly patched bitumen. This will be affected by the 'vertical' stiffness of the sidewalls on any given tyre, so stiffer sidewalls and lower profile (assuming this actually does represent a stiffer sidewall, which is probable) may be an issue for harshness at higher psi.

Centre tread wear? Do you notice any increased centre tread wear / tear when you track the car at higher psi? If not then you probably won't get any increase in this on the road. Keep an eye on it.

Do you find the higher pressures address your handling issues on the track? If not then it probably won't on the road either, but if yes then there's your problem right there!

Good steering response isn't only nice for hooning around (not that you should on the road), its nice all the time! Air is dead cheap, if you add more and don't like it then you can easily get rid of it. One thing to keep in mind, only use a good quality pressure guage and use only that one, if you use a cheap one, more than one, or servo station guages then you don't really know what the pressures are!

[JohnL]

With high pressures you may find the suspension becomes 'juddery' (especially on sharp bumps) no matter what damper setting you use, if so then its likely that the upper damper mount rubbers are too soft, as I described in an earlier post.

This is because the tyre is also a spring, and so are the rubber mounts (though they don't 'spring' in the same manner as the tyre or the actual springs because they don't support chassis weight). The tyre has some internal damping, but not much and less so at higher pressure. The damper needs to be on the stiffer side to adequately damp the tyre 'spring'. The damper cannot damp the spring action of the rubber mounts because the rubber is between the chassis and the damper, not between the chassis and the road. All we can do here is to stiffen the rubber mounts to lessen their 'springing' action, which also raises their harmonic frequency possibly taking this out of the range that will cause a problem.

To more fully explain about the upper damper mount:

Keeping in mind that rubber can successfully be used as a springing medium in place of a conventional steel spring (e.g. BMC Mini, Moke etc):

The upper damper rubbers act like an undamped short stroke spring that partially isolate the damper from the chassis, from the spring itself and from the road. This is only an NVH function and is damaging for suspension and chassis control because it means the (coil) spring is effectively partially undamped in part of its stroke, as is the chassis in initial body roll.

For good steering response the dampers are very important. The chassis should 'see' the dampers immediately any weight transfer starts to occur or INITIAL body roll will be increased and the onset of significant weight transfer will be delayed. However, with soft upper rubbers the the chassis doesn't 'see' the dampers properly until some roll has occurred and the rubber mounts have been loaded up to some degree. Soft damper rubbers also mitigate against adequate control of unsprung mass.

This is why 'pillowball' Mac strut mounts can increase steering response, i.e. the 'pillowball' eliminates the OE rubber upper strut mount, allowing the the chassis to 'see' the damper immediately as soon as weight transfer begins, etc.

[aaronng]

Just checked my pressures, they are 36psi. The 34 was when the tyre place filled them when they were not on the car.

Going too high tyre pressure on sydney roads = more lower back pain for me. Plus, my interior will shake itself apart.

I already have stiff suspension with pillowball mounts, so it is now all down to the tyre. I guess that is what you get with an asymmetric design with nice blocks on the shoulders but crap all and drainage channels in the middle.

[aaronng]

What have people heard about Marangoni Mythos? Someone in my work place said that they won motor mag tyre test this year? i don't get motor mag so i can't confirm.

http://www.marangonityre.co.uk/Mytho...D=2&Level2ID=1

I read that mag, but I don't think I'll pay over $400 a tyre when the competitors in the test ranged from $280-350. BTW, RE050 performed surprisingly well!

[DreadAngel]

GEEBUS!!! 1.6K everytime they run out =|

[SuperDave]

What have people heard about Marangoni Mythos? Someone in my work place said that they won motor mag tyre test this year? i don't get motor mag so i can't confirm.

http://www.marangonityre.co.uk/Mytho...D=2&Level2ID=1

That review was rigged. This is where the Mythos ranked out of the 6 tyres tested.
Dry Handling: 4th
Lateral G: 5th
Dry braking: 3rd
Wet braking: 6th
And it somehow won!? And they didn't factor in price, as it was one of the most expensive, or noise or life. From the tests the GS-D3, Sport Maxx or RE050A should have taken out the top 3 spots. For reference the other 2 tyres were Maxxis MA-Z1 and Falken FK452.