Why not stagger?

[Sailor]

I'll be looking at stagger after I finally get around to installing the Cosworth but only
if I find the rear is moving out too readily under power.
Then I'll need to look at the understeer that will probably be induced by the extra rear grip.
A real can of worms without the sort of money invested by BMW

[project.r.racing]

extra rear grip will not induce front understeer.

if you run wider rims with 'lower' offset to the front (ie increase the rear wheel track), it will induce oversteer.

[Sailor]

If the track remains the same, increase in rear grip will induce understeer.
Now if you want to start playing with offsets, scrub radius, spring rates, f/r weight bias, etc etc etc you will overcome the previously induced understeer.
BUT you may, and in all likelihood have, dramatically altered the dynamics of the vehicle ie, turn in, ultimate grip, transitional behaviour etc etc.

And yes the worms are by then well and truly out of the can and I have just enough knowledge to be aware of the pitfalls but not avoid all of them

Love to continue at a later time but I've got a 10CC concert to go to

[green_comet]

I have been running a staggered setup on my car for a few years now with no problems, 15x7 +25 up front and 15x8 +4 on the rears with 195's.
For me it was the best form vs function setup I could find, looks great and handles great. My last setup had wide and low offset wheels on the front and rear, this was causing the car to understeer quite a bit during hard cornering. Since changing the fronts over it handles really good now, might be a different story on a track but I wouldn't run this setup on a track anyway.


You can see the difference in this photo

[Mr_Q]

You'll get more grip out of your rear tyres by lowering the pressure than you will by going wider. All else being equal (tyre construction, etc), wider tyres don't increase the amount of rubber on the road.

If its just for looks though - go for it if you like it.

[bootz]

You'll get more grip out of your rear tyres by lowering the pressure than you will by going wider. All else being equal (tyre construction, etc), wider tyres don't increase the amount of rubber on the road.

If its just for looks though - go for it if you like it.

Whoa there, that sounds counterintuitive. You'll need to explain

One would expect 205's on an 8" rim would have greater rubber to road than 195's on a 7" rim. Otherwise performance cars would be going around on bicycle wheels.

The new Toyota GT86 has deliberately "skinny" 215's !

[Jimi]

If you go wider rears, be prepared to make a few trips to the alignment place - less negative rear camber should help a lot.

Most mx5s are running a lot more rear camber than front, so by putting wider rubber at the back you may/should be able to run less camber to keep it neutrally balanced. I see that as a big win - better braking and power to the ground with less camber.

I'm interested to hear how it goes!

[Aussie Stig]

I'n thinking that 205's on an 8" is a bit conservative, 215's on the rear would be a better fit.

Though with a norm asp car this is over tyred. For a turbo I can see advantages, The handling bias would be affected but with massive rear power it might be worth it.

Stunning car Green Comet!

[project.r.racing]

You'll get more grip out of your rear tyres by lowering the pressure than you will by going wider. All else being equal (tyre construction, etc), wider tyres don't increase the amount of rubber on the road.

If its just for looks though - go for it if you like it.

Whoa there, that sounds counterintuitive. You'll need to explain

One would expect 205's on an 8" rim would have greater rubber to road than 195's on a 7" rim. Otherwise performance cars would be going around on bicycle wheels.

The new Toyota GT86 has deliberately "skinny" 215's !

More goes into the rubber being on the road than just section width. Weight on the tyre, rolling diameter increase/decrease the contact patch size.

If you go a wider tyre but smaller rolling diameter, you may just have the same amount of rubber on the road.

the difference between a 195/50R15 and 205/50R15 is both a increase in section width and rolling diameter, so there would be a increase in the size of the contact patch. But it is not just the size of the contact patch that control grip. Tyre compound and how it is used with that contact patch is what determines grip.

The statement the Mr_Q made was very vague generalization. Yes there might be more rubber on the road, but it may not increase the grip levels. There was a thread recently on this forum that explained it in detail.

The FT86 or BRZ have a massive tyres that has a massive rolling diameters. The have use this to gain that little extra contact patch size.

[Hellmun]

Getting back to the original question, the mx5 is a 50/50 weight split car with low power. It was factory designed not to run stagger so by increasing track/tyre width on one side of the car you will change the overall balance. You can compensate in different ways via stiffening etc but it changes the overall dynamics again. I don't want to get too in depth as I'll be writing this post for an hour but if you cure understeer on the front by softening the front sway bar for instance, your actually dynamically moving more weight from the rear opposite corner of the car, increasing total chassis movement, changing rake angle etc. This can be good as you may achieve slightly more downforce from the front of the car from the further spring compression, or this may be bad as you now achieve bump steering as you've reached bad suspension geometry on the loaded corner. There are still many other factors that need to be considered and tested. Getting suspension right is incredibly complex and you very rarely get a net positive, it's all about finding the best compromise.

Just another reinforcement too that wider tyres do not give a larger contact patch, they change the contact patch shape all things being equal which will remove some longitudinal grip at the advantage of lateral grip. The big advantage to wide rubber is the relationship between grip and weight. As you add weight you gain more net grip from the tyre due to added deformation of the carcass, this is at a diminishing rate though as you can only squeeze the rubber so far into the road grooves before there is nowhere to fit it and the wider the tyre the lower rate in grip reduction is. Hence manufacturers of high powered heavy cars always run nice wide tyres. The mx5 is neither heavy nor overly powerful...hence it's quite happy with thin tyres without stagger.

That said I'm sure you can make stagger work if you really wanted but I'd rather just widen the track front/rear and tyre width together. My car run 15*8's with 225/50/15's and it's pretty grippy (seen >1.5g at the track). That said one big criticism I have of my car is insufficient power for the diff/tyres I have. The creates bad turn-in at low speed corners because of the locking diff and sticky tyres that won't slip which push the car wide. It's very good at high speed corners though...and most corners are 100kph+ so it's a compromise that's worth it for me.

[Mr_Q]

My comment was just that a wider tyre doesn't give you a larger contact patch, and therefore doesn't automatically give you better grip. All else being equal, a wider tyre will have exactly the same contact patch, but with a wider, shorter shape. This may give better cornering traction (which will depend on other factors too), but you might be giving up straight line traction (including braking).

Nothing comes for free.

[bruce]

I really doubt you would notice the difference in driving.
People fit big dished rims and don't complain that the track is all wrong.
If you want to do it, just do it. Green Comets car looks good with the stagger.

[Mr nanotech]

^^^^^^Yes!

[green_comet]

I think people just like to over complicate things, "By running a +45 offset all round your car will be better balanced and it'll go around a corner 0.3 of a second faster." Because the road is a race track, so you need to drive like a tool and push the limits every time you're on it. Just run whatever you like on the road, and get a set of 8" 6UL's if you're ever going to take it on the track.