What effect does wheel width have on handling?

[Ekona]

It's very easy to predict: If the driver doesn't change, and the road doesn't change, and you've added weight in the worst place, then unless you're capable of defeating physics the outcome will be a slower car!

[BobbyZ]

It's not defeating physics, because there's a bigger contact patch which provides more grip.

[ilogikal1]

It's not defeating physics, because there's a bigger contact patch which provides more grip.

 

And more resistance (not to mention the additional weight) hence more energy required to obtain the same outcome. Same energy = slower. Physics.

[BobbyZ]

It's not defeating physics, because there's a bigger contact patch which provides more grip.

 

And more resistance (not to mention the additional weight) hence more energy required to obtain the same outcome. Same energy = slower. Physics.

 

More weight = slower. Bigger tyres = more grip = faster. I think we agree on this. It would require complex calculations and / or back to back tests of specific set ups in specific conditions to determine whether you'd go faster or not, which was my original point.

[Stan350Z]

I'm still genuinely interested in why not as many people run 18s on front and 19s on rears, half the weight difference, wider rubber on the driven wheels to provide the extra traction and cosmetically must also look pretty sweet. My only assumption is that alignment and camber settings must need to be customised to optimise handling?

[Stan350Z]

If I was to upgrade from Rays I'd want to look into 18s/19s set up...

[Jetpilot]

I'm still genuinely interested in why not as many people run 18s on front and 19s on rears, half the weight difference, wider rubber on the driven wheels to provide the extra traction and cosmetically must also look pretty sweet. My only assumption is that alignment and camber settings must need to be customised to optimise handling?

 

Because you might as well just run 18's, 19 tyres will cost more than 18's if your burning through them on track and they wont really look any better staggered.

[docwra]

I'm still genuinely interested in why not as many people run 18s on front and 19s on rears, half the weight difference, wider rubber on the driven wheels to provide the extra traction and cosmetically must also look pretty sweet. My only assumption is that alignment and camber settings must need to be customised to optimise handling?

 

Because you might as well just run 18's, 19 tyres will cost more than 18's if your burning through them on track and they wont really look any better staggered.

 

Yep, mainly this, you also have to split two sets of wheels. But .........

 

 

It works, I definitely preferred the feel of 18's against 19's on the front and it definitely looked better than when it was on 18's all round.

 

Despite what looked like a contradiction up there, it is possible to have less acceleration, more grip and less steering feel all at once. The tyre width doesnt make as much difference as wheel weight, tyre compound oprobably has more effect than anything.

[monkeybrain1234]

I went from touring 18's to 370z 19in rays. Both with standard size tyres.

 

The 19's are certainly heavier particularly the rears, but do I notice a difference? Not really. Would say ride is a tiny bit harsher but nothing to write home about. For sure there is more grip but again it's not a night and day difference.

 

Where the key difference is the way the 19's look, they look great.

 

One piece of advice, the 19's do make the car look a bit tall, so I found some Tein springs help to lower the car and fill the gap perfectly.

 

Go for the 19's you won't regret it

[docwra]

The 19's are certainly heavier particularly the rears, but do I notice a difference? Not really.

 

Becuase they actually weigh about the same - the 19's are slightly lighter but the bigger tyres would offset that.

[Carbon.Ninja]

Interesting topic. In my mind (correct me if I'm wrong) acceleration probably will be more sensitive to tyre mass considering the are further away to the center of rotation therefore high inertia?

 

In the end all the physics we can't disregard, there is always a element of subjective evaluation and factors. Objectively you can measure by data like lateral G in a set environment (as much as weather allow) but consistence of driver would probably a big variance! I doubt anyone can day they are consistent unless they are professional driver. To further complicate the matter, even if we assume everything is accurate and measurable , driver confidence is the key. As the driver have to be confident in the car in order to push!

 

I guess the best approach for us as average Joe driver, is taken into account of law of physics as a starting point then fine tweak by subjective evaluation. Of course some maybe more previledged to have more sophisticated equipment other than human accelerometer (back side in my case) to tell what the car is doing..

 

Rant over lol.

 

Sent from my Nexus 6 using Tapatalk

 

 

[docwra]

Great post ......... physics isnt subjective though. Less unsprung weight leads to better performance, thats a fact.

[StevoD]

there is no answer to this thread really until you tell two wheels are to be cmopared but then its wheel vs wheel not 7j vs 9j as there will be 9j wheels lighter than 7j wheels

 

ie enkei rpf1 9j vs some cast wheel mania 7j

[StevoD]

And that grip will be blunted by the extra weight, so you'll actually be slower.

 

so why do time attack cars run stupid wide wheel with like 295 r888 on a 10.5j when a 265 r888 on 9.5j would in your case be faster?

 

im guessing its yes it take longer to get a wider wheel/tire up to speed and a maybe more numb feedback but you can carry more speed around a corner with a wide set up than a skinny

 

Edited August 25, 2016 by StevoD

[Ekona]

Exactly. Grip above all other considerations.

[StevoD]

Exactly. Grip above all other considerations.

 

so the out come as you said of it being a slower car isnt quite true

Edited August 25, 2016 by StevoD

[BobbyZ]

And that grip will be blunted by the extra weight, so you'll actually be slower.

 

so why do time attack cars run stupid wide wheel with like 295 r888 on a 10.5j when a 265 r888 on 9.5j would in your case be faster?

 

im guessing its yes it take longer to get a wider wheel/tire up to speed and a maybe more numb feedback but you can carry more speed around a corner with a wide set up than a skinny

 

 

Because stance, bro

[docwra]

Exactly. Grip above all other considerations.

 

so the out come as you said of it being a slower car isnt quite true

 

Grip =/= speed, the car with less unsprung weight will be faster in a straight line but slower round the corners.

[Flashback]

Hmm all very interesting so as there's only a certain speedd you can really get to on the roads then really a much wider wheel set will be better for me to have fun in the corners. 👊
[BobbyZ]

Hmm all very interesting so as there's only a certain speedd you can really get to on the roads then really a much wider wheel set will be better for me to have fun in the corners. ������

 

Depends how you define fun. More rubber on the road will give you more grip.

[Flashback]

Hmm all very interesting so as there's only a certain speedd you can really get to on the roads then really a much wider wheel set will be better for me to have fun in the corners. ������

 

Depends how you define fun. More rubber on the road will give you more grip.

 

Well if your saying sideways or facing forwards as the fun definition then I see your point that more grip might not necessarily equal more fun.

[Ekona]

No, what he means is that a car that moves around a lot can be a lot more fun than a car that grips and grips.

 

I deliberately ran my old MX5 on the crappiest tyres I could find, simply because it was far more entertaining that way. Speed & grip != most fun.

[Flashback]

I think that was kind of what I meant, just not very well put.

[Flashback]

OK guys so I got the wheels coming now, so what would be the best tyre to go on it..... not stretched just a really good fit and hopefuly with a fairly neutral effect on the speedometer? I went 19x9.5 et22 and 19x11 et25 in the end.

[BobbyZ]

I run 255/35 and 285/35 on 9.5 / 10.5 ET25 which sit pretty square (more so on the rear), so you'd be fine with that.

 

Edit: no guarantees regarding rubbing as you're a tiny bit wider than my set up, but I think you should be okay.

Edited September 11, 2016 by BobbyZ