Tyre sidewall rolling in corners question.
Discussion
I have a Citroen Saxo VTS with some Toyo T1RS on the front which I take out for the occasional trackday.
Looking at some other T1rs on a Peugeot 205, they seem to have the same issue to some extent as mine, with the sidewalls getting pretty involved in the action.
Anyway, here is the question; tyre pressure. I am getting sidewall wear on these tyres, quite far round onto the sidewall. I did one trackday on around 24 PSI. Having had some of this wear, I tried the next day I did at a much higher 31 psi to stop the tyre folding over so much.
On viewing my extreme wear on the tyres, one old timer (who is usually right) said that giving more pressure on the tyres doesnt always get rid of or help sidewall wear or this kind of folding over effect as at a lower PSI the tyre has a chance to change shape and adapting to the road surface. This seems to make some sense, what do people think?
(I cant directly compare the wear as the second day was on the same set of tyres but with much tougher shocks and slightly more solid springs, so this has thrown the results a bit, so more info would be good).
Looking at some other T1rs on a Peugeot 205, they seem to have the same issue to some extent as mine, with the sidewalls getting pretty involved in the action.
Anyway, here is the question; tyre pressure. I am getting sidewall wear on these tyres, quite far round onto the sidewall. I did one trackday on around 24 PSI. Having had some of this wear, I tried the next day I did at a much higher 31 psi to stop the tyre folding over so much.
On viewing my extreme wear on the tyres, one old timer (who is usually right) said that giving more pressure on the tyres doesnt always get rid of or help sidewall wear or this kind of folding over effect as at a lower PSI the tyre has a chance to change shape and adapting to the road surface. This seems to make some sense, what do people think?
(I cant directly compare the wear as the second day was on the same set of tyres but with much tougher shocks and slightly more solid springs, so this has thrown the results a bit, so more info would be good).
Its the tyres to a great extent.
We made the mistake in using T1-R/S for our first couple of track days.
They have very soft side walls (for the track)- as a road tyre they are pretty decent.
You can try pumping in a bit of PSI, but essentially you will need a decent set for the track.
We currently use Yokos Spec 2- not much roll on side wall.
Once these are bald, its R888 time!
Happy tracking,
BM
We made the mistake in using T1-R/S for our first couple of track days.
They have very soft side walls (for the track)- as a road tyre they are pretty decent.
You can try pumping in a bit of PSI, but essentially you will need a decent set for the track.
We currently use Yokos Spec 2- not much roll on side wall.
Once these are bald, its R888 time!
Happy tracking,
BM
Edited by Brian McGee on Tuesday 3rd August 09:59
I am siding with the not good for track thing here- I did do a day on Yokohama S-Drive's previously and these dont seem as good. The S-drives never had this problem either (which i forgot about).
The kind of 'fins' of the T1Rs get bent over when they are new as well, so you get some pretty strange wear on them.
The kind of 'fins' of the T1Rs get bent over when they are new as well, so you get some pretty strange wear on them.
Do yourself a favour and get a cheap (but straight) set of alloys in the smallest size you can fit over your brakes and stick some 888's or similar on them. Swap them over at the track so you dont have to worry about getting home if you damage a wheel/tyre on a curb plus you can run them down to the canvas if you so wish.
Jon Doe said:
I have a Citroen Saxo VTS with some Toyo T1RS on the front which I take out for the occasional trackday.
Looking at some other T1rs on a Peugeot 205, they seem to have the same issue to some extent as mine, with the sidewalls getting pretty involved in the action.
Anyway, here is the question; tyre pressure. I am getting sidewall wear on these tyres, quite far round onto the sidewall. I did one trackday on around 24 PSI. Having had some of this wear, I tried the next day I did at a much higher 31 psi to stop the tyre folding over so much.
On viewing my extreme wear on the tyres, one old timer (who is usually right) said that giving more pressure on the tyres doesnt always get rid of or help sidewall wear or this kind of folding over effect as at a lower PSI the tyre has a chance to change shape and adapting to the road surface. This seems to make some sense, what do people think?
(I cant directly compare the wear as the second day was on the same set of tyres but with much tougher shocks and slightly more solid springs, so this has thrown the results a bit, so more info would be good).
Some of your problem could be down to the way in which you turn in!! If you are agressive on the brakes, leap off them quickly before you turn, you will transfer so much weight over the outside wheel, the tyre wants to "roll over"! If you ease the the breaks off as you turn, you will prevent the amount of "weight transfer", keep the front of the car flat, and therefore eliminate the understeer which I guess you are creating!! HTHLooking at some other T1rs on a Peugeot 205, they seem to have the same issue to some extent as mine, with the sidewalls getting pretty involved in the action.
Anyway, here is the question; tyre pressure. I am getting sidewall wear on these tyres, quite far round onto the sidewall. I did one trackday on around 24 PSI. Having had some of this wear, I tried the next day I did at a much higher 31 psi to stop the tyre folding over so much.
On viewing my extreme wear on the tyres, one old timer (who is usually right) said that giving more pressure on the tyres doesnt always get rid of or help sidewall wear or this kind of folding over effect as at a lower PSI the tyre has a chance to change shape and adapting to the road surface. This seems to make some sense, what do people think?
(I cant directly compare the wear as the second day was on the same set of tyres but with much tougher shocks and slightly more solid springs, so this has thrown the results a bit, so more info would be good).
ginettajoe said:
Jon Doe said:
I have a Citroen Saxo VTS with some Toyo T1RS on the front which I take out for the occasional trackday.
.
Some of your problem could be down to the way in which you turn in!! If you are agressive on the brakes, leap off them quickly before you turn, you will transfer so much weight over the outside wheel, the tyre wants to "roll over"! If you ease the the breaks off as you turn, you will prevent the amount of "weight transfer", keep the front of the car flat, and therefore eliminate the understeer which I guess you are creating!! HTH.
Only asking as this is an area I feel I could improve on a lot.
I'm sure Howard will correct me if I get it wrong but my understanding is roughly this...If you're going quickly enough you shouldn't need the throttle until you hit the apex of the corner. What you're doing is easing off the brakes as you turn in (i've heard one instructor describe it as braking to the apex, rather than the turn-in point) and then rolling onto the throttle gradually to balance the car & then exit. You don't need heel& toe for that (plenty of threads on that already). If you're burying the throttle before you hit the apex then you're going in too slow and can take a bit more speed in 
grahamn said:
ginettajoe said:
Jon Doe said:
I have a Citroen Saxo VTS with some Toyo T1RS on the front which I take out for the occasional trackday.
.
Some of your problem could be down to the way in which you turn in!! If you are agressive on the brakes, leap off them quickly before you turn, you will transfer so much weight over the outside wheel, the tyre wants to "roll over"! If you ease the the breaks off as you turn, you will prevent the amount of "weight transfer", keep the front of the car flat, and therefore eliminate the understeer which I guess you are creating!! HTH.
Only asking as this is an area I feel I could improve on a lot.
edh said:
I'm sure Howard will correct me if I get it wrong but my understanding is roughly this...If you're going quickly enough you shouldn't need the throttle until you hit the apex of the corner. What you're doing is easing off the brakes as you turn in (i've heard one instructor describe it as braking to the apex, rather than the turn-in point) and then rolling onto the throttle gradually to balance the car & then exit. You don't need heel& toe for that (plenty of threads on that already). If you're burying the throttle before you hit the apex then you're going in too slow and can take a bit more speed in
It's called trail braking. It's used in any car that is prone to understeer (which includes most modern road and some race cars) to eliminate (or at least dramatically reduce) the understeer. Normally, if you brake hard and turn at the same time you will spin. Trail braking is effectively doing this in a mild and progressive manner but keeping it under control. You are using the weight transfer to exert more downward force on the front wheels, and less on the rear, giving the fronts more bite and loosening the rear, which will make the car turn more sharply.You should always come off the brakes smoothly and progressively "squeezing them off" to prevent the front of the car leaping up in the air and unweighting the front wheels, no matter what. In trail braking you do the heavy braking in a straight line, but you keep some pressure on as you roll the steering wheel into the corner, and you gradually ease the brake off, to keep some weight over the front wheels. To do this properly you need to carry more speed into the corner to compensate for the fact that you are braking longer and deeper, otherwise you'll slow the car down too much.
How far you brake into the corner depends on the car and the corner. In some cases you do brake right into the apex, in others you only brake a little past the turn point. In some cars you don't do it to eliminate understeer, you do it because you can and it's faster.
I would still agree with others that you should look at more negative camber and different tyres. Because although a lot of understeer can be driver induced, Saxo's like many other FWD cars inherently understeer.
timarnold said:
I would still agree with others that you should look at more negative camber and different tyres. Because although a lot of understeer can be driver induced, Saxo's like many other FWD cars inherently understeer.
Not strictly true; all FWDs have power understeer, but the saxo/106 chassis is famous for being "tail happy" on trailing throttle and under braking. I would think the fastest way round would be to use that characteristic rather than attempting to dial it out as the car as is can be balanced on the throttle. Slightly over-rotate the car into the corner under braking, and then be on the throttle a little early to correct the slide to make the apex, thus avoiding flooring the accelerator with the steering on lock, would seem to be the sensible solution.
Re Toyo Tyres, TVR had a "special" spec which was basically a harder sidewall.
Re Braking, think about coming off the brakes as the cornering pressures kick-in. In this way, the suspension gets compressed when braking starts & stays compressed through the apex as brakes fade out but cornering pressure comes in.
Get it wrong & the suspension is compressed, released, compressed, released !
Getting a smooth transition is a skill but a beautiful thing !
Re Braking, think about coming off the brakes as the cornering pressures kick-in. In this way, the suspension gets compressed when braking starts & stays compressed through the apex as brakes fade out but cornering pressure comes in.
Get it wrong & the suspension is compressed, released, compressed, released !
Getting a smooth transition is a skill but a beautiful thing !
davepoth said:
timarnold said:
I would still agree with others that you should look at more negative camber and different tyres. Because although a lot of understeer can be driver induced, Saxo's like many other FWD cars inherently understeer.
Not strictly true; all FWDs have power understeer, but the saxo/106 chassis is famous for being "tail happy" on trailing throttle and under braking. I would think the fastest way round would be to use that characteristic rather than attempting to dial it out as the car as is can be balanced on the throttle. Slightly over-rotate the car into the corner under braking, and then be on the throttle a little early to correct the slide to make the apex, thus avoiding flooring the accelerator with the steering on lock, would seem to be the sensible solution. maybe this is a something to try further down the line when the OP is comfortable with trail braking?grahamn said:
chris7676 said:
Surely 24 psi for the fronts is way too low for a nearly 1 tonne car anyway ?
Quoted pressure for the TVRI'd imagine unless the OP is running big alloys the profile of a Saxo tyre is much larger, with much less sidewall support so I'd agree that 24 PSI on track does seem unusually low.
The advice usually given is drop your pressure 4-5psi COLD to compensate for the extra temperature / pressure. Perhaps this has been miscommunicated to the OP.
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