Different rubber size fronts vs back??

wun911 · Postby **wun911** » Wed Aug 13, 2008 11:47 am

I like these weight saving ideas. (puts the flame suit on)

Anyone run like wider 215 at the back and stock 205 at the front on a 6.5 wide rim??
So I get more grip at the back where its needed. You dont need to the added weight of wider rubber on on the fronts. And you still get good responsive stearing.

Anyone run lower profiles on the fronts compared to the back so they get less side wall fex, and save some weight less moment of inerita due to smaller diameter etc etc!
I presume sidewall felx occurs more on the fronts than on the rear?? The spedo will still be accurate because its taken from the rear wheels??

In these situations have your alignment specs changed compared to oem stock setup?

Adam_NAclubman · Postby **Adam_NAclubman** » Wed Aug 13, 2008 2:12 pm

215 on a 6.5 Ewwwwwwwwwwww

wun911 · Postby **wun911** » Wed Aug 13, 2008 3:26 pm

Oh is that dangerous??

You know the deal the most amout of rubber on the thinest rim possible to save weight...

bruce · Postby **bruce** » Wed Aug 13, 2008 4:29 pm

Wun, come back to reality !

Charlie Brown · Postby **Charlie Brown** » Wed Aug 13, 2008 5:06 pm

215s on a 6.5" rim will flop around like Granny's undies on a clothesline and cause even more grip problems.

If you have rear grip problems I’d suggest that the tyres you have on the rear at the moment are stuffed or you need to look at your suspension. Never run a different width tyre front to rear on a MX-5.

Postby **mx52nv** » Wed Aug 13, 2008 5:37 pm

Charlie Brown wrote:215s on a 6.5" rim will flop around like Granny's undies on a clothesline and cause even more grip problems.

If you have rear grip problems I’d suggest that the tyres you have on the rear at the moment are stuffed or you need to look at your suspension. Never run a different width tyre front to rear on a MX-5.

100% agree (except in nfs13b's case)

Benny · Postby **Benny** » Wed Aug 13, 2008 6:46 pm

I'm running 215's on the back and 205's on the front, but I have 7' wide rims.

You have to be careful about the overall diameter fo the 215 tyre though, as some 215's are noticeably taller than the same tyre in 205.

I think 215's should be OK on a 6.5" rim, but you will notice they look a little "baggy", however, being baggy will mean that when you scrape the curb, the tyre will get scraped and not the wheel.

205's used to be factory fitted to 6" rims, so 215's on a 6.5" rim should be fine.
If you find them a little squirmy, add more air to stiffen them up.

marvis · Postby **marvis** » Wed Aug 13, 2008 8:28 pm

215 on a 6.5 is pretty crazy imo.

I would be doing the opposite to this for less rear end grip (But i don't know a whole lot

) (i have never dríven a 5 before so may be different specs if i have)
205 50 r15 on front (8" or 7.5")
195 50 r15 on rear (8.5" or 8")

What size rim and profile are you running and looking to run (or the idea)

marvis.

wun911 · Postby **wun911** » Thu Aug 14, 2008 4:12 pm

Yeah im having a bad experiece with loss of grip on the rear wheels (stiff suspension + crap years + winter roads)

I always thought side wall profiles were responsible for side wall flex. I thought like 50 profiles gave side more side wall flex than 45 prfile.

So I should get 7 wide rims and stick 215 onto them? that should give more grip than a 205 on a 6.5 rim?

stevesports · Postby **stevesports** » Thu Aug 14, 2008 6:06 pm

under what conditions are the tyres losing grip wun? Also note that having a larger contact patch might affect the handling of the car.

Adam_NAclubman · Postby **Adam_NAclubman** » Fri Aug 15, 2008 1:12 am

You won't get a larger contact patch, just a different shape

marvis · Postby **marvis** » Fri Aug 15, 2008 1:31 am

^ and sidewall stiffness.. Won't be noticeable but on such a small increase.

stevesports · Postby **stevesports** » Mon Aug 18, 2008 12:17 pm

Adam_NAclubman wrote:You won't get a larger contact patch, just a different shape

hmm? the way that i see it, if the tyre is wider, there is more tyre that touches the road, and as such a lrger contact patch.

StanTheMan · Postby **StanTheMan** » Mon Aug 18, 2008 12:51 pm

if you dump in a few bags of concrete. It will increase your contact patch.

The designers and engineers all say a wider tyre does not increase the the contact patch it only changes the shape.

with peeps like 13nfs who has a huge amount of power for a drag car. not sure how it works different. but its different.

I assume you have a pretty standard car. Satandradish power output. I'd be thinking about going back to 205 size Tyre but maybe with a softer compound or just a better quality tyre. & maybe change your geometry( wheel alliugnment) if you are having problems keeping the car on the road.