Do wider tyres improve handling?

[touge rolla]

Wider tyres also decrease the track width (If offset is roughly the same)
So running a staggered set up as an MR2 does for example results in a narrower track width at the rear of the car. This somehow affects handling in a way I don't completely understand any more than the knowledge that my car drove like arse when all four wheels were the same. Although this may have had something to do with it being on gtst wheels...

[allencr]

Yes, if not too wide for the rim.
No, if under-inflated or on water, snow, whatever.

[2jayzgte]

I tell you what having under inflated wide tyres in the wet comprimise's handling big time.In the wet you actually want less rubber on the road so it cuts through the standing water basically running 3-4 psi more a corner stand the side walls up a bit more helps big time.

I run the wets on my race car at about 20psi higher starting pressure than my dry tyres.

Should have been a bit more accurate there as I have not used a full wet before.My only experience at the track is with road tyres in the wet and by giving them an extra 3-4 psi over normal did make a difference.

Are you suggesting I should try a even higher PSI per corner??

[Mr Ree]

Matt probably means that he starts his dry tyres around 20, and his wets around 40.

You are probably running 38-40 in your road tyres on the track if its wet, so you will be in the right ballpark

[gt4dude]

depending on the car, factory equip may or may not be adequate

generally the high performance version of your car (if exists) will have factory specified optimum goodness

eg, 195 or 205 for a regular Celica, 215 for an SS-3 and GT-4

so any of the lower models will be great up to 215 for maximum traction and nimble handling.

on my gt4, 215 still gives the best nimble handling, but due to my increase in power, 225 holds better straight line traction at the expense of a little bit of nimbleness, especially cornering in the wet, 225 gives me understeer/oversteer the whole car slides far too wide under throttle.

also i've tried 205 tyres and they have worse effect on cornering, braking and accelerating

so theres a sweet point in tyre sizing for every different car its different. more can be just as good/bad as less

[Grrrrrrr!]

Wider tyres also decrease the track width (If offset is roughly the same)

Not with either definition of track width which i've seen used.

If you use the (most common) centreline to centreline definition, then track width doesn't change unless offset changes.

If you use the outside to outside definition, then wider tyres = wider track.

[touge rolla]

^ You are right I worded that all wrong.
I was referring to centre to centre track measurement
Staggered set up whilst the width from the outside to outside being the same between front and back = narrower track at rear.
Offset being roughly the same I was referring to standard SW20 offsets for what reason I don't know.

[matt dunn]

Matt probably means that he starts his dry tyres around 20, and his wets around 40.

You are probably running 38-40 in your road tyres on the track if its wet, so you will be in the right ballpark

Yeah sorry, wets I run 4psi5 as a starting pressure as they don't build as much as tyres in the dry,
dry tyres will increase 6 or 7 psi when hot from starting pressure unless you run nitrogen.


As for tyre size,
a wider tyre on a narrow rim will be worse than a narrower tyre that is on a correct rim size.

And increasing Dia is better than increasing width IMO.

[touge_ae101]

hey matt, that is very interesting.. do you run a full wet or just a good semi for a wet?

we have a set a hankook wets which are yet to be used bought a season ago after 2-3 wet meetings but has never rained at a meeting since! good luck omen we recon.. hah but would be good to know if 40-45psi will work if we ever get to use them..

[matt dunn]

hey matt, that is very interesting.. do you run a full wet or just a good semi for a wet?

we have a set a hankook wets which are yet to be used bought a season ago after 2-3 wet meetings but has never rained at a meeting since! good luck omen we recon.. hah but would be good to know if 40-45psi will work if we ever get to use them..

I have a set of semi's with a good pattern and good tread.

[KinLoud]

I understand that treaded tyres work best in the wet when the tread blocks have a sharp edge.
I've run 2 sets of Toyo RA1's
New set are my wets
Older (less tread, tread block edge rounded) are my dry tyres
When the the wets lose their edge they become dry tyres and I buy a new set for my wets.

Ken