For my case, i changed to smaller diameter tyres, as a results, my speedo reading show around 10-15km/h faster than actual speed,

althou in city traffic i gain better fc but on hiway my fc is quite bad because i have to rev more..previously for 110km/h(actual speed on gps) need to rev around 3k now almost 4k rpm so i would imagine it will be
another way around if i change to bigger diameter tyres than stock size

Bro, you forgot to include braking la. I think heavier or lesser size with the original will also affect brake efficiency.
I plan to experiment beyond 3% rule and see how is it.

Higher fuel consumption. Lower performance (acceleration, top speed suffers). Handling can be improved (less walking of the tyre), or worsened (if the suspension can't cope anymore and the wheel is in the air there is simply no grip at all). Also say goodbye to comfort, since yes, higher unsprung weight can upset the suspension setup, and also the tyre itself is a suspension when you use a reasonable size. The bigger the rim, the less the tyre absorbs, and that makes a big difference on the comfort (I've experienced it on a Touran with 15 or 16" steel rims vs Touran with 17" alloys... the smaller one was much more comfortable).

Wider tyres should result in better grip while driving in the dry, though FC is yet again higher. Steering becomes a bit harder too, especially at low speeds/stand still. In the wet a wide tyre is more likely to swim, though there are obviously good ones that can take a lot of water, and bad slim ones that can't.

Lower performance and higher FC can be countered with with very lightweight rims, but those are even more costly.

To me the disadvantages easily outweight the advantages, so I'm happy with 14".

Watch that TG video someone linked to earlier. More than 3 seconds faster on a short race track, just by using smaller rims. And look at F1 tyres. They use 13". IndyCars, which are less regulated, use 15". That seems to be a good size.


This post has been edited by kadajawi: Jan 12 2013, 01:18 PM

tramlining

http://www.caranddriver.com/features/effec...nd-tires-tested

bigger not necessarily better,,,,,

especially on our local lauyah roads

id recommend tyres with ~100mm/4" sidewall regardless of tyre size for local use
a balance between comfort/performance

e.g
165/60r13 = 99mm sidewall
195/50r15 = 97.5mm sidewall
205/50r16 = 102.5mm sidewall
225/45r17 = 101.25mm sidewall

This post has been edited by malutapimau: Jan 13 2013, 03:21 AM

F1 & Indycars use small diameter rims/thick tires as part of their suspension movements as well to absorb the bumps cuz their suspension is already ultra stiff.

Lets summarize them don't we;
(assuming total diameter doesn't change)

Benefits;
Looks
Can mount better tyres
Better handling, grip and braking (from wider tyres)
Can mount bigger brakes


Cons;
Expensive tyres
Increased weight (unless you buy expensive forged wheels) from both wheels and bigger tyres
Reduced fuel economy (wider tyres are heavier and has more rolling resistance)
Tramlining (from wider tyres)
Looks (looks silly with tiny brakes)
maybe more noisy (due to wider tyres)
higher chance of wheel damage from less sidewall height
comfort is reduced from less sidewall height


Basically there are only 3 good reasons to go with bigger wheels. I dont think looks alone is a good reason especially weighing in the downsides.

Going +1 (14-15") is possible a good thing, +2 is overkill.

This post has been edited by jaycee1: Jan 17 2013, 10:37 AM

How to maintain? your overall size is so much bigger. From 165/60/13 to 225/45/17 the overall diameter is 100mm MORE.

There, he said it =D

My stock Satria had 185/60/14. Ever since an engine swap to the 1.8, I've had the 195/50/15 partly because I needed the wheel clearance to fit evo twin pots in.

After so many sets of tyres and hard driving I still didn't think it was worth it going to 16s. The car already handled pretty good on the 15s. Rare finds but 205/50/15 is just as wide as the 16"s normally for protons.

I rather spend money on good 15" tyres than cheap 16" tyres.

In fact I can get ultra stiff and grippy 15" semi slicks for the price of a half decent normal 16"

@jaycee

those are examples of good comfort+performance tyresize for different type car, not one model one make car,,,,,

e.g
165/60r13 = 99mm sidewall (kcar tyre)
195/50r15 = 97.5mm sidewall (midsize/ b-segment)
205/50r16 = 102.5mm sidewall (c-segment)
225/45r17 = 101.25mm sidewall (performance car

after reading all these, mayb ill stick to my stock rim size which is 16' (inspira) lolz

you can go +1 (16-17) without much ill effects other than more expensive tyres.

Ultimately, it is up to you what you are looking for in new tyres.

If you put comfort above all else, then stick with 16s, if you want a bit more road handling, then good 17" tyres is a good compromise.

Increased Control over Acceleration, Steering and Braking
With lighter wheels, the weight of the vehicle’s rotational mass is reduced. This allows more precise input
and directly affects the vehicle’s response in terms of acceleration, steering and braking.

Controlled Cornering .

And the air flow is to cooling the brake is improved

but of coz the fuel consumption will be affected.