This is just funny.
I somewhat run chrome on mine, but it is the SBC and I dare anyone to tell me they aren't "race" series. Enkie RP03 Things weigh 18.2 pounds so I'm pretty sure going up to the 20's could be around 20 pounds or less.
Weight aside the tire is factored into the equation. Sorry, but unless you are ripping the bead how would it not matter? ALTHOUGH I will say that you also must account the tire becomes oblong when sitting. How oblong does it become?
Also can we please take "air in the tire" out of the picture? Unless you are filling it with cold air on a hot day. You don't weight more when you breath do you? Air is air and doesn't have a weight. Take a bottle. Weight it empty. Crush the bottle and weigh again. Same weight.

All things aside, dude with the 3rotor has chrome. Enjoy your chrome who really cares what someone else says? If you care so much you are probably driving the wrong car. OR look into SBC and everyone should stop.

 

...i roll 20 inch chromes on my mazda 8,
when i go by the clubs all them girls say yay

 

ok so if you aint beefing up the motor or anything than there is nothing wrong with the 20's. i dont think its would be that great a ride if you was flying down d highway on 20's. But if its your show piece/cruiser car then why not. do wat you want. me personally just not my cup of tea. its your car. throw some 26's on that thing for all i care. You can put a lift on it ant everything. I mean y not?

 

you either bought the wrong car or the wrong rims, so return one or the other

 

Their ugly and heavy and God kills a kitten every time someone puts a set on an 8.

 

air has no weight??? are you sure, or is it just because in most instances its uneasily measured?

if its true, we would all be floating right now...

don't say that its fact when it isn't buddy... remember air has different volume depending on elevation and moisture. hope you didn't forget that...

 

Chrome rims makes me think of Fried Chickens, guys driving in hoodies, cheap cologne and gangsta rap. Meh. Not my style.
The only compelling reason for increasing the wheel size is to accommodate big brakes and provide adequate air flow to them.
I personally think SUVs with their ridiculously large 22" what have you in chrome finish over cookie size brakes look absurd.

 

The only thing you've said that is correct is that air has weight.

http://www.engineeringtoolbox.com/mo...air-d_679.html

Dry air is more dense than humid air.

For Air:
Now if we assume worst case scenario, say air pressure is ~34psi and temperature is about 0 degrees Fahrenheit, this would make the air the most dense.




ρ = 1.325 pin Hg / TR
ρ = 1.325 * (69.232+29.924) / 459.67
ρ = 0.2858 lb/ft^3


Now for the weight difference between rims. Well known that a density times a volume will equal weight.


Volume for a 20 inch rim with a 3 inch tire height (on each side) for a total outside diameter of 26 inches, and lets assume a 9 inch wide tire.


The volume will be pi*(13^2-10^2)*9 in in^3.


Divide that by 12^3 ft^3/in^3 and you get a volume of:


1.129 ft^3


This gives the weight of air in a single tire with a 20 inch rim, 3 inch tire height, 9 inches wide, at 0 degrees F at 34 psig to be:


0.322 lbs.


All four tires:



1.291 lbs.




And no, people in space float because there is less gravity, not because there is no air.


Air has a different volume based on its container, not because of it's elevation.

 

If the overall diameter is the same, and the weight is the same, the only other thing to consider I would think would be how the weight is distributed. More weight towards outside of wheel will require more work to build momentum than weight concentrated towards the inside of the wheel. Ya'll are going way to deep. Who's going to take their 20 inches of bling onto the track anyways?

 

It's pretty obvious that 20 inch rims will have a higher rolling resistance than than 18 inch rims.

Kersh4w has it spot on.

 

right. that's called inertia. and this is the point i wanted to make after i posted.

if you have a solid metal disk, and it weighs 20lbs. and a 24" circumference. and lets say that weight is perfectly distributed.

and another disk that looks like a bike tire and the 20lbs (also 24" circumference) is mostly concentrated around the outside edge.

guess which one has less inertia?

the one with more weight around the outside edge. so it doesnt really matter that the outside rolling diameter is the same. plus sizing your rims is not the ideal thing to do if performance is your goal.

this discussion is thought about a LOT by companies that design lightweight flywheels.

as i said. hold 10lbs 1 foot from your chest and then 3 feet from your chest. the weight didnt change. but the effort sure did.

 

You armchair physicists and engineers are technically correct...larger diameter rims move more weight outside and require more effort to turn, and more effort to change direction (over bumps or in turns). So technically it takes away from performance.

With that said, you are debating things that make little to no difference in real world day to day street driving. IF we were discussing strictly racing applications for maximum effort, high speed driving, then most of what is said here would be correct. For the street, it really doesnt matter that much. You might notice a little rougher ride over bumps (due to the lower sidewall flex and extra weight) but that is about it. The car will still drive the same...you could test drive 2 rx8s, one stock and one with 20's, and if you were blindfolded when you were put into the drivers seat, you would not be able to tell which was which in terms of street driving.

I just think it is funny, but pointless, to debate this **** like absolute performance is a matter of life and death, when in reality most of these cars never see speeds over 85mph and zero competitive driving.

 

^ End.

 

im going to go ahead and say at least 25% of us go to some sort of track on a regular basis. and im going to say at least 50% of us have seen some sort of competitive driving at least once. and im going to say at least 75% of us do enough spirited driving to notice the difference in rims+tires. i definitely notice the difference in acceleration with my winter tires and my summer tires. they not only have a larger rolling diameter, they are also heavier.

i honestly dont care what zumn puts on his ride, but if he is going to come on to the forums and tell us that his car defies physics... well im going to say something.

 

I'm going to have to call BS on that one. Not that many of us live in such close proximity to road courses, and we don't drag race these cars. That leaves autox, which is usually only held in larger cities.

If you had a way to poll the membership of this forum and get honest replies from all of them, I'd bet the number is far closer to 5-10%. It may seem that a higher percentage of the users of this forum are track junkies, because the hardcore race/modificaion guys are the more prominent and memorable posters. The "regular" owners who just drive their cars don't know as much, don't post as much, but definitely make up the majority.


Wait, wait. This is the same forum where we have a whole crew dedicated to sackriding traffic citations. The same forum filled with members who chew out any poster who complains about getting a ticket for a minor traffic infraction, while claiming they always obey laws and do not speed or drive aggressively. The same forum where the mere mention of n impromptu street race can get your thread deleted.

And now you want me to believe that 75% of this same membership drives their car hard enough on a frequent to discern a 1-5% increase in unsprung mass?

So which is it...are we the golden boys of the highway, always buckled up, driving the speed limit, using our turnsignals to change lanes, frowning on anyone who openly admits to driving a little fast and getting a ticket for it...or do the majority of us drive our car at 9 10ths frequently enough for a small change in wheel/tire setup to be obvious to us? We can't have it both ways here.

I think the issue is being far overstated in this thread for the purpose of supporting the OPINIONS of those who do not like the larger wheels and tires.

 

I love you.

 

can i just say one more thing?

they look ghey.

 

^ rofl.

and we are DEFINITELY not the golden boys of the highway. all that talk is simply forum rules and politics.

i've been to the top of 5th gear, "on my families private 5 mile long air strip."

 

Wow, I missed a lot but read it all, interesting points and someone said "for everyday driving you wont see a difference" and that is correct. However i think that person also mentioned "feel the bumps more and a rougher ride", the only bumps I ever feel are when i change lanes on the freeway. , its really a smooth ride! Im on 35 series if I was on 30 or even less than yeah maybe. But 35 series is borderline before you start feeling bumps. Someone also mentioned that the wheel carries more weight on the outside because of the bigger rim? I kind of dont get this or clear up my thought please....If I have a lip of 3-4 inches which would put the face/rim more in the center of wheels drum....would that make a difference?

 

no, you want all the weight to closer to the hub, not the drum.

As far as differences in feel, i felt a huge difference when i switched from stock rims to gramlights, which are about 17lbs per rim at 18x8.5, keep in mind that lighter rims you might not feel the difference in acceleration but it will help with braking, handling and tire wear.

but honestly, plenty of people have put on heavier rims on this forum with no problems at all, a lot of ppl run cheaper brands like tenzo or konig which tend to be heavier in construction. Also there are a bunch of people running 19s or 20s with some of the more expensive brands too, and no one really commented on theirs either. I think the reason why you get so much flak from the forum is because your rims look like they belong on an escalade.

personally i dont mind chrome, my next set might also be chrome, but i do mind weight. In the end its your car, if you choose to destroy the performance aspects of your car because it looks cool, you shouldn't have to care about what i think.

 

98% of all statics are made up on spot.