Why are staggered wheels better than wider all around?

[doctorwedgeworth]

Pardon my newbie ignorance here. I'm used to cars that look nice but aren't anything special under the hood.

I know you should have as wide wheels as possible on the back to increase grip going into corners, but why does it matter what's at the front? I'm asking because I currently have some spare tyres so I have:
2x 205/40Z17
2x 215/40Z17
4x 215/40R/17

At the moment I have the 205/40Z17 on the back and the 215/40Z17 on the front (not sure why they are the wrong way around, going to to swap them today) but I could take these spare tyres down and have 215/40/17 all around including spare.

I know it should be rims, not just tyres, but is it worth having wider at the back if really it just means you're reducing grip on the front? Can someone explain why?

[SonicSW20]

The cars suspension geometry is designed for wheels that are wider at the back, and tyres that are wider at the back. The rear weight bias and the fact it's RWD is also a reason for this. Front / rear bias is not decided solely by tyre width.

If you go too wide tyres at the front, you will find that on an average road, it will tramline excessively. This effect will get worse the wider you go.

More importantly, what make / model are these spare tyres, and how old are they? MR2's really benefit from decent tyres.

[doctorwedgeworth]

Ah ok. Thanks for explaining about the suspension. The two 215s that are on it now are accelera alpha, 205s at the front are Silverstone. Spare is autogrip and I'm guessing the other three are too. All of the tyres have been sat for 3 or 4 years but were almost brand new - the four spares came off a celica with a cracked alloy. I'd only just replaced the tyres on that celica when I noticed the alloy and replaced all of the wheels with stock.

[2mad]

215/40/17 and 235/40/17 is the rule of thumb for 17"'s i ran 245/35/17 on the rear .. looked pretty good ... basicly what ever your front widths are for your alloy run 1" wider for the rear .. what ever you tyres width is for the front run 20mm or more for the rear ..


Best of luck