Tyres: Size vs Performance

[dieselhead]

I'm curious to find out what you guys think, is size more important than performance/brand when it comes to rubber. You know, the stuff that goes on the rim.
Got my car with from the dealer on 18" Eagle F1s, thinking lots of torque require lots of grip. I think a stock CDTi sits on 205/55/R16, quite a bit narrower than my 225/40/R18. I got to a point when I needed to replace my tyres. Thinking that an AH on 18" has sufficient grip on cheaper rubber, I bought a pair of Roadstones at the front. At the back I already got a pair of Maxxis a couple of months ago. It is impossible to get to the limit on public roads, so I can't appreciate how much grip I lost on these cheapies compared to the fantastic F1s.

Question is, have I got more grip now on these cheap 225/40/R18 than on some highest quality 16" rubber? What do you guys think?

[Havabigjuan]

good question, looking forward to the range of answers...

I always went narrower hp tyres over width but that was on bigger cars like commies etc, thinking that the better tyre was worth more grip

Probably not as big an issue with these smaller opel's, so maybe mid price width might be better or comparable to narrow hp

though i don't change tyres at the rate some do as my car isn't driven as much as it used to be...

[iNiff]

wider is going to be better as there is more rubber on the road at anytime
lower profile offers higher grip and a harder ride where higher profiles can take a bit of a hit without affecting the suspension too much.

and as for not being able to go anywhere near the limit? just because you cant do 200km/h doesnt mean you cant push the limit of grip.

edit: and as for brand names or costs, you might save $100 now but you may be halfway through your second set when you could be still on your first had you spent more

[dieselhead]

well, i don't agree with the last remark. high performance rubber lasts less due to softer compound. better grip means less mileage...
i also think that rotating, balancing and aligning every 7,500km is much more important than brand and model.

[lithium]

both are equally important!

i used to have Nankangs aka Nan-*Bangs* on my 205/40s...slid all over the road in the wet and even in the dry my tires would slip on hard acceleration. worse grip than the factory tires on 185/50s.

i now have a set of Dunlop Sportmaxx on, and they've never slipped once, not even powering out of a sharp corner in the rain. they're phenomenal, these tires find the limit of my driving ability far before i can find the limit on them

[lithium]

well, i don't agree with the last remark. high performance rubber lasts less due to softer compound. better grip means less mileage...

agreed. often less than half the mileage of normal tires...

[J]

Well generally, for the same tread, a wider tyre will grip better on dry asphalt, but a narrower tyre will grip better on wet asphalt, or snow (which, a wider tyre will try to match by having bigger, deeper grooves and/or higher % of silica content). Not sure about sand, gravel or rocks...?

Thus getting a wider, poorer-gripping tyre might not make too much of a difference in the dry, but in the wet, the grip threshold will be much reduced! Ok, so we might not be driving on ten tenths around corners all the time, but I pray that no one here needs to emergency brake on wider, poor-gripping tyres on wet sealed roads!

[iNiff]

well, i don't agree with the last remark. high performance rubber lasts less due to softer compound. better grip means less mileage...

mm agreed. I think i was thinking basic range brand names VS no names. still i got a bit carried away.

[Greg K]

very good question Dieselhead!

i would imagine that you would the same grip now, or slightly better now compared to when you had the original 16's on. even though you have a wider tyre, the original 16's might have had a better gripping tyre overall, only if you kept to the same size tyre now.

I had eagle F1's on before and they were fantastic! for a perfomance tyre, they didnt wear down not as nearly as quick as what i thought they would!

I just put on some Dunlop 3000A's on the vec. I know i could have saved a couple of hundred dollars going for a cheaper alternative, but i also didnt go to the other end of the scale and buy something rediculously expensive like Continentals. I found a tyre in my budget that wasnt to bottom of the range but also gave me the piece of mind that if im ever in a "sticky" situation, i think i will have a better chance of not having an accident due to the better grip...

i hope what i just said makes sense... lol
:)

[digifish]

Just for the record, the stock 205/55 R16 Touranzas on the CDTi are excellent. Particularly in the wet.

There was a tyre comparison done by wheels recently...

http://www.wheelsmag.com.au/wheels/site/articleIDs/AC2AA4A17833CC00CA25745000255724

http://www.wheelsmag.com.au/wheels/wheelsed.nsf/6f41c1d13a3b1f07ca256c2700808185/aca08a6e9b900661ca2574500024e038/Body/0.4CCC?OpenElement&FieldElemFormat=jpg

[rjastra]

Another point to think about is that even though you may get better grip with wider/lower profile tyres you can upset the natural balance of the car. It grips more but doesn't feel as nice to drive.

Usually you hear people moaning about cheap rubber..."it never wears out so I can't justify replacing the sh*t tyres"

[cbrmale]

There are two aspects to size. The first is that wider tyres obviously put more rubber on the road. The second is that wide low-profile tyres (say 225) are marketed as a sports / high performance tyre, and usually have a softer and grippier tread compound than a 'general purpose' size (which these days is 205 on 16"). It's the combination of the two which makes the difference. Even a cheap 225 probably has a grippier compound than a narrower general purpose tyre, cheap doesn't mean lack of grip (but may mean shorter tread life).

My view is that the expensive tyres (Continental, Michelin etc) often have a better grip/wear balance than cheaper tyres, which may grip well but wear out quickely, and cheaper tyres may also be noisier.

There is probably a third aspect in play, and that is a wider tyre needs to clear more water from the tread on a wet road, so by nature they need to have better wet weather performace than a narrower tyre or else they will aquaplane.

My SRi has the same suspension settings as a CDTi (but with less front-end weight). I am astounded by the grip of my Continental 225 x 17's. Without going anywhere near its limits, in the dry I corner at least 20-30% faster speed than all other drivers, and in the wet I corner much faster than most drivers would on the same corner in the dry. These Continentals, based on the first 20,000km of wear, should last somewhere between 50,000 to 60,000km (rotated every 7,500).

[rjastra]

My SRi has the same suspension settings as a CDTi (but with less front-end weight). I am astounded by the grip of my Continental 225 x 17's. Without going anywhere near its limits, in the dry I corner at least 20-30% faster speed than all other drivers,

Why are you astounded? You have more tyre on the road than a 1800kg Commodore Omega yet weigh 500kg less. You car should stick to the road.
You could argue that 225/17s on a 110kw Astra (or any small car) is more a fashion statement than a handling imperative.

Remember that some of the best hot hatches in recent history (less than 10yrs) have done the job on tiny 195 or 205 width tyres! :) And the mighty MX5 still survives on rather narrow tyres.

http://www.youtube.com/watch?v=KtpsKV-8C_k

[Shaun]

Theres an old saying. You pay for what you get. Spend $100 per corner of the car and it stands to reason you will end up with a tyre thats not going handle as well as $500+ tyre. Compound plays a big part in tyre wear. The Contis fitted to a VXR from factory tend to wear harsher towards the end of the life. Meaning they compound is softer towards the end the end of the tyres life.

I recently put Yokohama Advan's on the VXR which cost me just over $2000. Yeah sure i could have put a cheaper tyre on the car but at the risk of no front end grip.

It comes down to what type of car you have and driving style. If your putting rims on for looks then a avarage run of the mill tyre will do fine. But if you wish to push the car in corners where loads on the side wall and degravation of the tyre is going to be caused by use then look at going for a more expensive tyre.

But saying cars arent on the limit on a public road is alittle incorrect. Take a car for a drive up the Putty road @ Legal speed limits through the coners and then feel the how warm the rubber is. And thats on a Public road at legal speed limits. Friction is caused every time a tyre rotates ans friction causes heat meaning wear will take place.

[entice]

Being a forum...

I disagree with a lot of teh stuff written above.

Saw a study once.. done on evffect of tyre width and grip.

A wider tyre also doesnt mean more rubber on the road. In effect, it means a wider tyre footprint, but a shorter one.. in essence, teh same amount of rubber on teh road at one time. What we're all forgetting, is that the wider tyre will deform less to support the weight above it.. hence, a shorter footprint. especiallyu when you consider most +1, +2 +3 applications usually end up with higher tyre pressures, in effect, you end up with less rubber on teh road.

So, I disagree.

A narrower spec tyre of higher quality would be better IMO than a wider cheaper one.
several reasons to add:
1. higher quality control
2. better rubber compound
3. better sidewall / construction
4. less drag / rolling resistance


Also, the conti's on my SRI were good..and teh Michellins on the diesel are rubbish.. but in the wet the Michi's seem to hold on better in corners.

Notye the use of teh word seem.
Perhaps that because they are softer sidewalls, and have more flex.. whereas teh conti's just are more informative...

[my_Berlina]

Usually you hear people moaning about cheap rubber..."it never wears out so I can't justify replacing the sh*t tyres"


Isn't that why burnouts were invented ?