[Miata] 195/60s vs 195/50s

[the.jack]

> -----Original Message-----
> From: glen mccready [mailto:gkm+miata at petting-zoo.net] 
> Subject: Re: [Miata] 195/60s vs 195/50s
> 
> Specification  Sidewall  Radius  Diameter  Circumference 
> Revs/Mile  Difference
> 195/60-14         4.6in  11.6in    23.2in         72.9in       869        0.0%
> 195/50-15         3.8in  11.3in    22.7in         71.2in       889       -2.3%
> 
> So, the 15in setup will give you slightly lower gearing, the 
> gearing may help acceleration, but that assumes you keep the 
> unsprung weight comparable (ie. buy wheels that weigh the 
> same or less than your 14s). The 15in setup also has 
> significantly less sidewall which should help turn-in 
> response, but also means you're effectively losing some 
> spring rate from the tire so if you think the ride is harsh 
> now, stick with the 14s for more sidewall. And it gets more 
> interesting when you consider what rim width you're going to 
> stretch the 195mm patch over, so that's a whole other story...
> 
> Clear as mud?
> 
> glen
-----Response-----

	I knew about the .8" difference in sidewall (thus less spring), I just realized that I'm not sure of the stock 5-spoke 14s
width... I was thinking 6", but they might be 5.5... The 15s would almost definitely be 6.5, and the weight might actually go down:
considering Heliums and (as I mentioned) Hankooks which would be (ignoring tolerances and balance weights) 29.4#, versus 31# with
the 14" Hankooks and the 12.5# stock rims (also, as you mention, they are a touch taller, so that weight is through a larger
radius...)... In anycase I'm considering the weight difference close enough not stay up all night worrying.
	Also, FWIW, I have 195/60s (Ziex 512s) on there now and they "bulge" a bit too much for me, so in that respect the 195/50s
on wider rims would "sit better" on the rim (to me).
	I guess I'm looking for a "subjective" comment on the differences. I like my steering response and the ride isn't too
important to me (still on stock suspension) as my Miata is basically a DD for me, most long trips or anything with "cargo"
(shopping, visiting, etc) are done in the SAAB, so I can skimp on the "luxury" aspects of my car :) But if I'm not actually going to
gain a lot of control or handling from the 15s then I'd like to add a sweet sounding exhaust over a new wheel/tire set.
	I think I mixed the muddy water up a bit :/

Chris C.
99 Mazda Miata 5-sp Emerald