Replacing both tyres?

[7db]

2. If so, then does this mean the car is biased towards understeer, and that exaggerating this by having crap tyres on the front will make it very understeery indeed? Perhaps if you want really neutral handling the rears should be just slightly down on grip?

Yes. But this is good. Oversteery cars lose control catastrophically at their critical speed.

[TripleS]

I do recall that when radial ply tyres first came into popular use we were warned that although they provided higher levels of grip than the cross ply tyres used previously, when radial tyres do finally lose grip they break away very suddenly and dramatically, and are much more difficult to catch and deal with safely - so they appeared to be a bit of a mixed blessing. Admittedly I'm talking about how I remember things from when radials like the Michelin X first appeared in the early 1960s. Quite possibly some years of development may have made their breakaway characteristics more progressive and manageable since then, but I really don't know, and I don't think I want to find out.

Best wishes all,
Dave.

I remember the first Michelin X's well. I had a set on my Citroen Light 15. They were indeed very grippy: until, one day, overconfident in their ability, and mine, I lost it on a left-hander somewhere near Banbury. As you said, they hung on till the last minute & then all four went. Fortunately the road was empty & I did my 360 deg. spin unimpeded. Later, I switched to Pirelli Cinturas (or were they Cinturatos)? which were a little less in ultimate adhesion, but a bit more progressive.

Hello, Chris.

I seem to think the early Pirelli radials were called Cintura to begin with, and then an improved version called Cinturato appeared later.

....but there was nowt wrong with the Dunlop RS5 Road Speed tyres anyhow, and them wuz cross plies!

....although I did like the improved fuel economy given by the lower rolling resistance of the Michelin X.

Best wishes all,
Dave - always a skinflint.

[crr003]

Now you could argue by reducing the grip of the rear tyres you're giving yourself a more neutral car, but if I were the one doing it (and I'm not), I'd want to have measurements of the suspension kinematics, full Pacejka coefficients for the tyres in question, full inertial properties of the car in all configurations, aerodynamic maps, power mapping curves and a whole raft of secondary things. Then, even with all that I'll have effectively made the car worse because the amount of overall grip available from the tyres is less.

If you're trying to improve the handling of a car, making one end crapper is not the way to go about it...

At the risk of a QI type klaxon going off......
What's dry grip got to do with tread depth?

[Mr Cholmondeley-Warner]

Cintura=belt, Cinturato=belted.

Seems they were originally called Cinturas, but Cinturato is more descriptive.

@DT - shouldn't that be "crappier" ?

[animalkit]

ok may silly to say but if you adjust your tyre pressures this will affect the handling charecteristics of a car (in the dry at least) much more greatly than a few millimeters of tread. 1-2 psi will mke a huge difference. if you find you car is understeering reduce front pressure little and increase rear pressure a little. if you have a front right tyre with lots of grip and a front left with less increase pressure of the tyre with the most grip and reduce the one with the least. i do quite enjoy doing this and seeing how it affects the balence of the car even at quite low speeds.i dont realy undrstand how car manufacturers can put recomended pressures i as srely different tyres need different pressures and im pretty sure there not so ignorant tat they think everyone will keep the same tyre mae of throughout the life of a car. surely the tyre manufactures and fitters should know the pressures for different loads/compounds and types of tyre?

[vannut]

Just to throw my tenpenneth in. In the days when crossplies were still on the go, why was it illegal to fit radials on the front and crossplies on the rear? (You could, however, fit crossplies on the front and radials on the rear) This included Minis....

The answer is.... because it's dangerous, because the radials will handle/grip better than the crossplies.

Incidentally, this is still a reason for an MOT fail.

http://www.motuk.co.uk/manual_410.htm







.

[Angus]

I confess that until recently, I'd always thought that the best tyres should be at the driven end. If the best tyres should be at the back, but for most people the fronts are replaced more often, is it laziness or ignorance by the tyre people that they don't swap tyres for you? (assuming the same size tyre all round)

I stand corrected. At my local, independant, tyre place, they had a poster up advising that new tyres should go on the back.