Wider wheels

[guss]

What would the advantage be In Fitting wider wheels I've heard the width doesn't mean you can actually corner or grip better so what are the advantages and reason would their be for alpina and hartge to offer 7/8 j wheels. can't be just that they look better surely

[Rtaylor2208]

I'm not sure that's really true. The more rubber at the rear on a RWD car that is in contact with the road can only provide more grip. You don't see any performance RWD cars running skinny rear tyres.

[Captain_Birdseye]

You'll notice a heavier handling, especially if the tyres are new and beafy and that might take a while to get used to but by the time you have got used to it and the tyres have worn down a bit you'll have a car that feels better in my opinion. If you run it with steels you have a more 'original' feel but slightly skittish on the wet corner. Depends, it's different, definitely different.

[Motorhole]

Yep wider wheels, wider tyres means more rubber in contact with the road and more mechanical grip in dry conditions. But more liable to aquaplane in the wet and increased unsprung mass.

[HairyScreech]

Conventional friction says the more area you have for the same force the less pressure per square inch, friction is related to pressure per square inch and the loss of pressure but gain in area mean your friction stays the same.

However tyres are not conventional sliding friction, this is where the myth of the grip staying the same comes from, tyres are actually interlocking friction like a gear.
Wider gears can handle more torque (give more grip) for the same reasons wider tyres can give greater grip levels.

As stated though its at the cost of greater drag, weight and chance of aqua planing.

[zd3bx]

Good thread, as I've been thinking myself whether there are any advantages/disadvantages of going for wider rims...I'm not a fan of putting 195 rubber on 9J rims, so that's why I was wondering if it would be worth going for, say 8J?

Even that seems a bit "too much", considering M3 had 7.5J? Not sure if that would make a massive difference?

Unnecessary stress on steering rack/driveshaft or anything like that? Silly handling or weaker performance?

[Brianmoooore]

'Wide' tyres absorb a surprisingly greater amount of energy than narrower ones - even more so in the wet.
As Hairyscreech says, in the basic equations for friction, contact area doesn't feature. The situation with tyres is more complex, but it's still not as simple as the wider they are the more grip there is. There's also the small matter that to provide any grip, the tread has to be actually in contact with the road - something that doesn't always happen with the average 'slammed' E30, where we often find the inner edge of the rear tyres on the canvas, with the outer edge still showing the moulding marks.

[mikelat]

Wider tires don't put more rubber to the road they just change the contour of the contact patch. There are only two ways to enlarge your contact patch, reduce your inflation pressure or make your car heavier.

[mikelat]

Wider tires don't put more rubber to the road they just change the contour of the contact patch. There are only two ways to enlarge your contact patch, reduce your inflation pressure or make your car heavier.

[HairyScreech]

some good reading here:
http://www.f1technical.net/forum/viewto ... =6&t=12762

However a lot of it just scratching the surface, if you really want to understand this issue then your looking at a lot of reading, prepare to have a sore brain.

[zd3bx]

To be honest, I would be more interested in how wider WHEELS affect the E30, in particular, rather than tyres.

As we all know, when people "in the scene" go for wider wheels, they don't necessarily go for wider tyres, because wider ones will rub, so you would normally see 215 tyres on a 9J rim, etc.

That's why I wanted to know if, say an 8J rim, would be suitable for an E30? Not talking about the fitment, but about how it feels/drives, compared to original 6.5-7J wheels.

Anyone?