Tire Dimensions and their FC/Handling/Comfort Implications

[hominid]

Mga bossing,

Wala po akong makitang thread na nag-eexplain talaga nito. Kaya eto na lang...

Sa pagkaalam ko, larger...

a.) Treadwidth = poor fc;better handling;comfort?
b.) Profile(depth) = poor fc; handling? better comfort
c.) Overall diameter = poor fc; handling? comfort?

Pakitama na lang po at kung pede ay paki-explain ng kaunti.

Me effect din po ba size ng rim bukod sa mas malaki, mas mabigat?

Salamat po.

[Memphis Raines]

So you're looking forward to bolting on some larger wheels eh? As far as I know, if you slap on either larger rims or larger tires/rubber you will have more rolling resistance which will have an adverse effect on your fuel consumption or "fc". As to the degree of how much will depend on the upgraded size, say, from 16" to 20".

Switching to larger rims (for more bling) with low profile tires will not only drastically affect your riding comfort, it will also put more strain on your brakes (rotors, pads) which is why the need to upgrade these are also necessary should you decide to keep that kind of set-up for good. Sadly, not all considers this and just keep their stock ones.

The chief benefit of a wider tread is that it can improve your handling. It helps you take on corners more aggressively and makes the straights more stable in terms of steering wheel feedback at high speeds.

[niky]

Wider tires will give you more grip, but they tend to wander more on rough roads at speed if they're too wide and/or too grippy.

Treadwidth: wider treads lead to poorer fuel consumption, better braking and handling grip, but a lower resistance to hydroplaning (wide tires hydroplane more easily than thin tires, depending on the tread design) and often more wandering over ruts and cambers on the road (tramlining, they call it... where the wheels try to steer you instead of the other way around).

But this is only down to a point... tires that are close to original width don't tramline as much or at all... and the effects are dependent on the rubber compound used.

Profile(depth): low profile tires have no effect on fuel economy, as long as you're on the same rim. If you have a 15" rim and 195/55 tires, when you go to 195/50, you're making the diameter smaller. Which makes the tire easier to spin and marginally lighter, increasing fuel economy. But this makes your odometer inaccurate, and it'll read too fast, so economy won't seem that much better.

Lower profile tires usually have less sidewall flex (again, dependent on design), leading to more stable handling (up to a point, if they're too thin, it might make breakaway too unpredictable).

The big disadvantage of low-profile tires is protection from bumps. Since they have less sidewall area to absorb impacts, they won't cushion your wheels and suspension from potholes as well, and busted "rims" and shocks can result.

Overall diameter: Try to keep it the same. As diameter increases, unsprung weight increases, which leads to poor comfort (tire and wheel dependent... some aftermarket wheels and tires are lighter than stock), poor acceleration (larger wheel, harder to turn), and poorer fuel consumption.

-----

Me, I made the conscious decision to increase my overall diameter a tiny bit. This worked to correct my odometer readings (based on GPS reference, it was over-reading by 5% on the stock tires, because it was set for the US size, which I swapped to). It made acceleration slower and handling suffered (bigger sidewalls), but it made the ride more comfortable (even at my preferred rock hard 35 psi pressures).

For the best reference in terms to size:
http://miata.net/garage/tirecalc

[v6dreamer]

Mga bossing,

Wala po akong makitang thread na nag-eexplain talaga nito. Kaya eto na lang...

Sa pagkaalam ko, larger...

a.) Treadwidth = poor fc;better handling;comfort?
b.) Profile(depth) = poor fc; handling? better comfort
c.) Overall diameter = poor fc; handling? comfort?

Pakitama na lang po at kung pede ay paki-explain ng kaunti.

Me effect din po ba size ng rim bukod sa mas malaki, mas mabigat?

Salamat po.

Go visit this site www.tirerack.com

[LotharWStrand]

Here's another question. My current wheel mount has a 5 bolt pattern. Is it possible for me to convert it to 6 or 8?

[niky]

Anything is possible. There are hub conversion kits for just such a purpose.

But it depends on what car you've got. If you've got a front-driver, it's not advisable, personally, because most 6 lug wheels (I'm assuming we're talking US 6-lug, for cars?) are designed with off-sets for rear-drive vehicles.