Tyre sidewall stiffness. Do you notice/care about it?

Tyre sidewall stiffness. Do you notice/care about it?

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Discussion

Kozy

Original Poster:

3,168 posts

179 months

Monday 20th January 2014
quotequote all
Seems to be a point of contention in people this one. Some are adamant that they must have a stiff side wall on their tyre, and a soft one ruins the handling. Others say nonsense, it doesn't make a difference, anyone claiming they can feel a difference on the road is talking rubbish.

My personal experience is this: For the last 12 months my MX5 has run on Uniroyal RainExpert tyres. They are/were superb in everything but wear, it seems that they had an incredibly soft sidewall and it collapsed under hard cornering meaning the outer shoulders got annihilated. I am not exaggerating either, they were gone in about 12 minutes from new (12 runs at an autotest).

I've just replaced two of them with Vredstein Sportracs, and these have a much stiffer wall. Where the uniroyal could be collapsed between thumb and forefinger, the Vred's barely deform with a full hand grip. The Vreds went on the front.

My initial reaction was as I expected, they rode a bit harder and the car turned in much faster, with less steering lock required for any given turn. It's become apparent though that by keeping the URs on the back, I have screwed up the handling somewhat. It becomes apparent over about 40-50mph on a straight road, the back end just feels wandery, like it's going to oversteer constantly. It never does though, when turning an actual corner the back end feels like it's stepping out before snapping into line and gripping. To me this feels like there's a massive delay between the front a rear slip angles generating, that wasn't there when the front sidewalls were also soft.

I had this once before on my Civic, I swapped the tyres front to back and problem instantly went away. I think that sidewall stiffness is a very real concern, however only if you mismatch on the axles.

Anyone else notice the sidewall stiffness at all?

s m

20,129 posts

164 months

Monday 20th January 2014
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Kozy said:
Anyone else notice the sidewall stiffness at all?
I think I certainly noticed this on Toyo T1R.
The AVS Sports had a very much stiffer sidewall according to the tyre fitter and to my mind the car 'felt' much better.

TommyBuoy

1,205 posts

128 months

Monday 20th January 2014
quotequote all
Yes and Yes.

RE050 MZ for the S2000 (sure that's right) have a very stiff sidewall and certainly notice the difference with a softer wall on turn in.

I care about it, but realistically you would get used to it and not notice after a while. So yes I care and yes I notice it but I have far more things that are more important smile

jamieduff1981

7,192 posts

101 months

Monday 20th January 2014
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Yes I notice. In fairness it does need to be a fairly extreme end of the spectrum, but by way of example, I absolutely hated the internet hero that was the Toyo T1R. There is a balance to be struck though. Rock hard tyres aren't ideal either.

300bhp/ton

39,286 posts

151 months

Monday 20th January 2014
quotequote all
Yes, when I moved to some Khumo's on the Roadster. Sidewall was much softer and it certainly affected the feel and turn in. To compensate I raised the pressures by quite a bit.

Off roading side wall stiffness is very important too, as you want the tyre to mold to the terrain.

jon-

16,074 posts

177 months

Monday 20th January 2014
quotequote all
I noticed it so much I started www.tyrereviews.co.ukhehe

There's more going on than just sidewall stiffness to give you the feel you talk about, but I agree it's a huge deal for me.

I actually prefer the Bridgestone S001s on my M3 to the Michelin Pilot Super Sport due to the feel, even though the raw grip is lower.

ETA: I've been trying to think of a good way of measuring sidewall stiffness and charting it for the public, I can't think of a good way of measuring it accurately though.

rallycross

11,068 posts

198 months

Monday 20th January 2014
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[quote=Kozy], anyone claiming they can feel a difference on the road is talking rubbish.
quote]

this to me suggets you havent got the first clue about what you car is telling you through the controls (unless you drive something devoid of any feel).

Krikkit

20,227 posts

142 months

Monday 20th January 2014
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I had a set of T1-R's on my Rallye, and although the soft sidewall was obvious when pressing on, once you got used to it they were great. Wet weather performance in particular was fantastic after a set of Yoko Parada Spec 2's!

Kozy

Original Poster:

3,168 posts

179 months

Monday 20th January 2014
quotequote all
rallycross said:
this to me suggets you havent got the first clue about what you car is telling you through the controls (unless you drive something devoid of any feel).
That's my take on it too.

Kozy

Original Poster:

3,168 posts

179 months

Monday 20th January 2014
quotequote all
jon- said:
I noticed it so much I started www.tyrereviews.co.ukhehe

There's more going on than just sidewall stiffness to give you the feel you talk about, but I agree it's a huge deal for me.

I actually prefer the Bridgestone S001s on my M3 to the Michelin Pilot Super Sport due to the feel, even though the raw grip is lower.

ETA: I've been trying to think of a good way of measuring sidewall stiffness and charting it for the public, I can't think of a good way of measuring it accurately though.
Fantastic website that is, bravo!

A sidewall stiffness rating would be fantastic. Can you not just measure the average spring rate with the tyre off the rim? Maybe an average rate and also a range?

Dave Hedgehog

12,972 posts

165 months

Monday 20th January 2014
quotequote all
very much so

i used to deliberately purchase yoko AVS's for my B5 S4 and RS4 as they had very poor steering feedback (zero on the S4) and the solid wall on the yoko's made a noticeable improvement

i had a set of uniroyal's on the RS4 and it bounced down the road like it was on balloons ...

Edited by Dave Hedgehog on Monday 20th January 13:05

SuperchargedVR6

3,137 posts

181 months

Monday 20th January 2014
quotequote all
Anyone who's had run flats will know all about sidewall stiffness.

Yes I've been buying particular brands of tyres based on sidewall stiffness for years. As already mentioned, the Bridgestone RE050 is a good one. Or I might choose a Conti Sport 3 or Eagle F1 A2 if I want the grip without the crashing over potholes. Horses for courses really.

I'm surprised there's no rating / classification for it on road tyres. There's a rating for just about everything else on a tyre.

jon-

16,074 posts

177 months

Monday 20th January 2014
quotequote all
Kozy said:
rallycross said:
this to me suggets you havent got the first clue about what you car is telling you through the controls (unless you drive something devoid of any feel).
That's my take on it too.
Always makes me laugh when they provide cars like the Audi A3 on tyre launches for comparison driving. Of all the cars they could pick, they provide one with zero dynamic qualities and less than zero steering feel!

Still, if you know what you're looking for, the difference is still easy to spot, even on dead cars.

iloveboost

1,531 posts

123 months

Monday 20th January 2014
quotequote all
Quote:
Where the uniroyal could be collapsed between thumb and forefinger, the Vred's barely deform with a full hand grip.

EH?! What the heck are you talking about?!

bobbo89

3,290 posts

106 months

Monday 20th January 2014
quotequote all
SuperchargedVR6 said:
Anyone who's had run flats will know all about sidewall stiffness.
Yep, my R56 MCS handles like a dog on its run-flats!

C.A.R.

3,676 posts

149 months

Monday 20th January 2014
quotequote all
He means you can physically - visually - deform the sidewall of the tyre by basically giving it a good hard poke.

I have always liked the Uniroyals but agree with everything said. I run Rainsport 2s and they always look a little bit under-inflated and the shoulders have almost worn right out whilst the rest of the tyre has 4+mm of tread in the middle.

On the road though I can't say I can feel anything untoward, to be honest they actually feel pretty good.

Tango13

6,045 posts

137 months

Monday 20th January 2014
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I fitted some Goodyears Eagle F1's to my e39 M5 and the soft sidewall completly ruined the handling, a mate who has the same car took mine out and was visibly whiter. It felt like the entire rear suspension was falling out.

I'm currently running Vredestiens with a very stiff sidewall and it's perfect.

Tango13

6,045 posts

137 months

Monday 20th January 2014
quotequote all
I fitted some Goodyears Eagle F1's to my e39 M5 and the soft sidewall completly ruined the handling, a mate who has the same car took mine out and was visibly whiter. It felt like the entire rear suspension was falling out.

I'm currently running Vredestiens with a very stiff sidewall and it's perfect.

Kozy

Original Poster:

3,168 posts

179 months

Monday 20th January 2014
quotequote all
iloveboost said:
Quote:
Where the uniroyal could be collapsed between thumb and forefinger, the Vred's barely deform with a full hand grip.

EH?! What the heck are you talking about?!
It's not hard. Take a tyre with no wheel rim.

Pinch the sidewall between thumb and forefinger. You could collapse/compress the sidewall like this.

On the Vreds, you had to use all four fingers in a proper grip to get it to compress.

I've seen photos before of someone standing on an upright tyre and it not collapsing. I assume it must have been a run flat?

Ozzie Osmond

21,189 posts

207 months

Monday 20th January 2014
quotequote all
This is all a load of cobblers. You don't need to buy tyres with concrete sidewalls to make a car go round a corner. All you'll end with is appalling ride quality all the time.

Neither is it any surprise that the tyres of a road car can be destroyed in a few laps of a circuit. That sort of thing eats both tyres and brakes. There's a reason why racing cars are built so much lighter than road cars. Car tyres can be protected somewhat by inflating to the upper end of the sensible range.