hi ebelibadi. just wta ur opinion on bigger sized rims. yeah they look nicer. and cost 'nicer' too. but what are the benefits we can gain from those? are they worth our manaayy?

u can fit good tyre on it because most of them good tyre start from size 17"

bigger rims usually mean wider rims...hence wider tires and also need to use lower profile tires.

this gives an advantage on the traction n handling side.

Handling is one thing, but despite of the size and weight, it might affect the petrol consumption due to increased weight.
Correct me if I'm wrong because I was being told for this info. :/

i heard the same too. wondering if its just another urban legend from the people who get jealous of other people who can afford bigger rims. but i think it does make sense. bigger wider rims = more mass = heavier = more petrol consumption. some say with smaller sidewall on tyre can also cause louder noise..... or is it?? the urban legends continue......until someone with experience come here and comment on this lah.

This post has been edited by adlirazali: Dec 12 2012, 04:21 PM

ok, no urban legends here base on my experience with 14" to 16" then settle down at 15", the reasons for dowsizing are the 16" tires are more expensive and if you're looking for low profile ones, the manufacturer will always treat those low profile tires as "performance" tires, hence gonna cost you more. low profile tires have small and hard sidewall, once you hit some big potholes...high possibility that it will hurt the sidewall and it's not repairable.

manada FC suffer, if your new bigger rims use low profile tyres and end up having smaller diameter than previous one, your car FC can even be better than before




due to inaccurate speedo reading

Providing if we are using good pair of rubbers. If something like Falken 522 or synergy m5. Then pretty much they are still crappy.

when u are in doubt. stay stock

stay stock, you cant outsmart the engineer, provided you are getting the right car for the right usage.

myvi-town
GTR-track
proton-highway.

Bigger rims (bigger diameter and width) do provide advantage in terms of handling.
-With bigger diameter, you'll need to use lower profile tires which has less flexing/stiffer sidewall than normal thick tires. This will give you more direct/sharper response, better grip during cornering, and increase stability/reduce the feeling of floating.
- Then the wider rims surely also need to pair with wider tires which of course gives you more footprint, so again improves grip even further.
- Wider & lower profile tires also are normally higher performance rated with better compound and strength for high speed, hence again you improve the grip and handling of the car. Of course there are still some bigger tires which are just big without really having better performance than smaller tires hence negates this advantage. For example, if you compare 17 tires from those cheap China brand tires with 15' Michelin, Yokohama, BS, GY, etc., then of course the 15' will still give much better grip.
- Finally some cars do really need bigger wheels because they have big power and need big brakes. Small rims will not be able to accommodate those monster size brakes, hence the big rims is mandatory.

Note though going too big indeed provides disadvantages if it ends up being way too heavy and tires too thin. The extra weight will reduce acceleration, worsen fuel consumption, increase braking distance, and actually might worsen handling due to more unsprung weight which the suspension has to control. If the tires are too thin like wafers then of course it sacrifices a lot of comfort and will hurt your back and also endanger your rims when hitting potholes, hence what's the point? That's why those big rims which are forged and very lightweight are expensive. An example is the set I'm using now. It's a 17x8.5 forged Japanese rims but only weight 7.5kg, compared to the standard 16x7 which weight 10kg! So despite going bigger and much wider, I still managed to save a few kgs and and improves my handling, stability, and cornering capability so much more than before.
So if want to go bigger, try to use the lightest rims you can afford and don't go excessively big (generally max +2 inch in diameter). For some cars, they already use big rims with quite low profile tires so that general rule does not apply and do not upsize the diameter anymore. Though you may increase the width if you want/necessary.

tldr; this

and maintain within over all +3% diameter than stock

watch this -->

http://www.youtube.com/watch?v=VYczUsb1A_I

Sorry didn't know how to embed. too lazy to try

actually i kinda agree. i always feel the rabid push to upsize the tyres is almost like a disease and many people end up using their 17" till its botak before changing.

our roads are not perfectly flat and running higher profile tyres that can deform to cater to the imperfection on the road surface actually makes more sense than running a super stiff tyre.

another thing is that pressure = force/area. so at a given pressure the contact patch on the road is the same regardless of how wide the the tyres are (ofcoz the compression and subsequent heating up of a narrower tyres is another issue altogether).

thicker sidewalls also means that bad roads are less painful to drive over slightly quicker.

last but not least, at 15" i can afford to change my tyres whenever they are at 50% and get new tyres and still be cheaper than those running 17" or even 16" until end of life.

It's like a nonstop trend that people keep going for bigger rims! Actually 17' is becoming rather conventional & not so big anymore now since many std cars already come with 17 or even bigger! Again it depends on your car size and how thick the tires should be to accommodate the rims. My car can still use >11cm tire sidewall even when using 17' without increasing the overall rolling diameter, hence the comfort is still good. Many std cars that come with 17 still able to be combined with rather thick tires too so that's fine. However many people just try to follow this trend no matter what car they drive, hence often become painful and actually worsen the car instead of improving it.

Btw no matter when I was using 15 or 16 or 17, I always use my tires until only about 20% left which is usually at the 4th-5th year of usage! Changing them while still at 50% is just still too much waste IMHO as they're still very good.

yup... and the other thing is bigger rims dun necessary mean nicer looking.

i've seen many damn big rims but no upgrade of brakes and hence end up with a big space between brake disc and rim, which optically make the disc appear even smaller than it is. imho. that is ugly.

i rather have smaller rims and this would make the disc looks bigger.

ofcoz taste is subjective, just stating my preference.

Agree! Small cars using big rims also IMHO looks out of proportion already!

out of proportion and slower to accelerate.

Is it just me or larger wheels (which is usually the case if you go for larger wheels) should actually improve FC since for a given rev on your engine, you could cover more distance. Of course, it's harder to accelerate because it's larger but while it results in longer brake distance it also allows better cruising ability. I am under the impression that larger wheels will improve FC - else everyone will opt for smaller wheels.

Well... as far as distance covered per revolution then yes. you cover more distance per turn of the wheel.

However, that is if you use oversize tires which you are not supposed to. when u increase the rim size you decrease your profile size to maintain the same overall wheel size.

but even if one decides to just screw the speedo calibration and just opt for bigger wheels, there are still too many factors to consider.

the most obvious is that air resistance means that the engine has to keep pushing to keep the wheel rolling and a heavier wheel is harder to spin regardless if the car is accelerating or cruising along as you have to constantly work against all the resistive forces. not forgetting bigger tyres require more torque to turn simply coz the radius is bigger.

one area where wider tyres might save energy is that it does not have to deform as much as thinner ones to maintain the same contact patch to the ground and hence less energy wasted in rubber hysteresis.

then there is also the question of air drag on wider tyres.

in conclusion, there are too many factors to consider whether a bigger diameter wheel will be more fuel efficient than a smaller one. and whatever i state above are extrapolated from conventional wisdom, and we all know how reliable is conventional wisdom so please improve upon/correct me if i got the concepts wrong.

I do not think the induced air drag due to the change of wheel width is in anywhere significant, although an increase in wheel height (which makes car taller) should make some difference overall - and probably only their engineers would know whether allowing more air through the floor would make a positive or negative impact.

And bigger tyres should be beneficial for cruising because it can carry more energy on itself thereby taking longer time to lose its 'charge'. The only major setback is the reluctance to accelerate from rest but once you get the wheel moving it should be alright.

Of course, we should be aware that suspension setup etc. will make an effect and that could affect FC as well.

Anyway, let's do some calculation - given there's an inch gain in diameter when you opt for an inch bigger (just assume the side profile is same for old and new rim size). To travel 100km, old tyre (say 15" rim with 185/55) will need to revolve about 54,000 times while new tyre (with an inch gain in diameter) will revolve about 52,000 times, a 4-5% gain in lesser revolution. If just pure cruising (which eliminates the more reluctant to start from rest deficiency), this gain should be pretty accurate. Whether the other factors will offset this gain will need to be carefully experimented only can know - and will also differ between cars for even more factors. LOL!