Notes On Upgrading Tyre/rim Size

Hola · September 13, 2006

Hi All,

Im sure there are some duplicate threads on this topic. But Just need to see your views in a more focused technical angle....

Lot of car owners upgrade their rim size from their original size to a bigger size using low profile tyres to mainly to gain looks. Today a tyre shop owner who is realy an expert told me that increasing the tyre size from from 13" to 15" may harm the shocks in the long run. He says even though the final diameter is matched with the help of low profile tyres there is lesser shock absorbence from the rubber are minimized to the rims which directly impacts the shocks. This worries me as the Vios we got uses a 17" and I thought of going for a 15" soon for my EK3 too.

And he says the information on maximum tyre size in terms of diameter and cubic is indicated on the side panel of the driver area (seen it, but some in Japanease). What are your expereinces guys? Will a increased tyre size damage your shocks? Is that why some expert owners upgrade their suspension system when they upgrade their tyre size? Does this mean we have to purchase good looking alloys which maintains the original rim size?

Whats your view?

Hola

neXGen · September 13, 2006

Well.. i am NO expert on this but yeah i ve heard of issues where guys ve changed their alloys and installed 17' along with some low profile tyres.. it does improve handling over on smooth roads.. the disadvantages are the cars with this have more repairs for the simple reason our roads are not meant for a "smooth" riding.. the extra rubber in normal tires help in assisting resisting the shock from potholes and thus the lack of rubber leads to the shock absorber doing all the hard work.. unless you have got some heavy duty off-road shocks i doubt whether your car will be in a stable "no-piece-falling-off" condition if you get what i means..

changing the alloys for performance/handling gains is acceptable but not under the costs of added vehicle maintenance which just makes it an extra burden on most o ours already harden up wallets :-)

but yes.. it looks REALLY cool but is just NOT meant for our roads ;-)

Zz

Edited September 13, 2006 by neXGen

Newbi · September 14, 2006

Hola said:

Hi All,

Im sure there are some duplicate threads on this topic. But Just need to see your views in a more focused technical angle....

Lot of car owners upgrade their rim size from their original size to a bigger size using low profile tyres to mainly to gain looks. Today a tyre shop owner who is realy an expert told me that increasing the tyre size from from 13" to 15" may harm the shocks in the long run. He says even though the final diameter is matched with the help of low profile tyres there is lesser shock absorbence from the rubber are minimized to the rims which directly impacts the shocks. This worries me as the Vios we got uses a 17" and I thought of going for a 15" soon for my EK3 too.

And he says the information on maximum tyre size in terms of diameter and cubic is indicated on the side panel of the driver area (seen it, but some in Japanease). What are your expereinces guys? Will a increased tyre size damage your shocks? Is that why some expert owners upgrade their suspension system when they upgrade their tyre size? Does this mean we have to purchase good looking alloys which maintains the original rim size?

Whats your view?

Hola

I'v got low profiles on 15' rims and all I can say they are vary uncomfortable on bad roads. You could feel any rut on the road and on our roads this can be a very hard ride.

Vtechman · September 14, 2006

Hola! Yes it's true.....the ride is more uncomfortable the bigger your rims get. Our roads are also not good enough for 17's but when it comes to 15's I think there is no prob especially on a standard weight car like the EK3. The problem gets worse when you got a bigger car that is way heavier. The weight of the car coupled with a big rim can give the shocks and suspension a lot more work. BUT your VIOS again is a light car so there should not be many issues with a 17" provided you look after your tyres and make sure the recommended air pressure is very well maintained. I myself ran my EK3 on 15"s and at the end of the day you want to keep them on for good cornering and road holding on them HONDA's.

Hola · September 14, 2006

Well thank you for the info. I was talking to a friend who got a Suzuki Swift, that pandithaya has fixed 15" for that too. And now he is crying about lose of comfort. But for that we can say the car is not fit enough for a 15".

Also I got a friend who got a VIRS, well he got original set of 15" where he claims he got no issue, but then again he got sports suspension.

So what I understand now is that when we have to put up a increased diameter of alloys we got to modify or upgrade the suspension as well. Which of course will cost another extra thousands....

Vtechman said:

Hola! Yes it's true.....the ride is more uncomfortable the bigger your rims get. Our roads are also not good enough for 17's but when it comes to 15's I think there is no prob especially on a standard weight car like the EK3. The problem gets worse when you got a bigger car that is way heavier. The weight of the car coupled with a big rim can give the shocks and suspension a lot more work. BUT your VIOS again is a light car so there should not be many issues with a 17" provided you look after your tyres and make sure the recommended air pressure is very well maintained. I myself ran my EK3 on 15"s and at the end of the day you want to keep them on for good cornering and road holding on them HONDA's.

The Vios is quiet all right in comfort, I think for the price we paid, which was nearly 2.5mil at that time it was still over priced but it had lot of geniune mods from indicator meters, body kit, spoiler, 17" alloys. I have to check if the shocks are modified accordingly. And i think it should be becuase the ride is smooth

gunat · September 14, 2006

Well, simple physics would definitely state that the ride should get harder, just because there's less rubber between the road and the rim.

Having said that, i just upgraded from 14" to 16", and surprisingly my ride improved slightly...which i can only attest to the tires. Something to be said about spending a little extra on a well known brand.

Although, there's no doubt in my mind that my suspension is working harder to keep everything in check.

As most have elaborated in this thread, size and wieght of the car play an important part, but i think correct maintenence of the tire also contributes to a good ride...

porkster · September 15, 2006

gunat said:

Well, simple physics would definitely state that the ride should get harder, just because there's less rubber between the road and the rim.

Having said that, i just upgraded from 14" to 16", and surprisingly my ride improved slightly...which i can only attest to the tires. Something to be said about spending a little extra on a well known brand.

Although, there's no doubt in my mind that my suspension is working harder to keep everything in check.

As most have elaborated in this thread, size and wieght of the car play an important part, but i think correct maintenence of the tire also contributes to a good ride...

Hey dudes,

Simple physics EXACTLY! Ok this is my expereince and my 2cs worth on this. Most us folks go and put big ass wheels n tires but don't think about what lies beneath. A suspension system is a highly sophisticated sereis of components that come together to give a certain drive feel to a vehicle. Some of us have stock RS suspensions which come with sports springs, matched shocks, sway bars and ride control (eve electronic, this controlls the damping force of the shocks). Most of us don't. So when we upgrade one part we overlook the other connected components and end up suffering.

From my expereince I had crapola 14s on my car when I got it and the tire size was 195/14 60, I then upgraded to 195/14 55 but noticed the ride was still the same. Once I got a bit more flo jo I got me some 16s and added 205/50 16s but still the ride comfort remained the same. I did on purpose upgrade the springs, sway bars front n rear and shock mounts. This gave me a harder stiffer ride but I was OK with that because I needed to be able to put the increased engine power on the the tarmac effectively and not lose control. Now I have upgraded to 17s with 205/40 17ZR......still waiting for the wheels to clear so I will post how the ride feels. Also my shocks have manual adjustable damping so I set them to soft and this improves the bump by quite a bit.

My conclusion is this, if you're going to increase your tire size, n rims etc....at least put in heavy duty shock mounts. Secondly I ran an even tire pressure of 28psi and noted that this is the best for daily driving in crap roads. For performance I went with a 32/34 setup and feel the control is a bit better but the ride definitely harder. So if you guys ae running fat ass rims suggest you go with the slightly lower pressure of 28 all round.

Cheers, Porky

noaim · September 15, 2006

Hola said:

Well thank you for the info. I was talking to a friend who got a Suzuki Swift, that pandithaya has fixed 15" for that too. And now he is crying about lose of comfort. But for that we can say the car is not fit enough for a 15".

Also I got a friend who got a VIRS, well he got original set of 15" where he claims he got no issue, but then again he got sports suspension.

I got 15" on the March! I do feel almost all the potholes n bumps on the road.

porkster · October 4, 2006

monamonu said:

I got 15" on the March! I do feel almost all the potholes n bumps on the road.

Hi Monamu,

What's the tire pressure you're running and the size of your tire (ex. 195/55 R15)?

Cheers, Porky

noaim · October 4, 2006

porkster said:

Hi Monamu,

What's the tire pressure you're running and the size of your tire (ex. 195/55 R15)?

Cheers, Porky

195/50 R15...

lokuputhaa · February 12, 2007

I didn't get a chance to read everything above...but here goes:

by increasing the size of the wheels, the tire wall profile reduces while its rigidity increases to compensate for the reduced flex boundaries. So in turn, the tires would send through more shock form the ground...which is basically like increasing your spring rates....

this is why stronger shocks are advisable with lower profile tires, as is the case with sports springs.

you don't really need new shocks...but some original spec shocks may not be able to handle the increased shock forces and could break.

Hola · February 12, 2007

Many of the guys who got their tyre size upgraded says they had issues with their shocks. And they say when they replace their shocks they are fine. Is there a diffrent kind of shocks or pressure of the shocks we should follow when we upgarde the rims? Any one knows further of this?

Devinda_Z · February 12, 2007

i up-ed mine a long while back from 14" to 15" on an AT192 CArina n the results were AMAZING

didnt sacrifice comfort n got é car feeling"tighter" - excellent aorund corners.. i dont think 1" makes all that much impact but like echoed above - 2~3" without corresponding mods is aksing fr trouble

as for shocks - i belive there r diffrent types for different applications but even fiddiling with é springs might have a noticable impact...

neXGen · February 12, 2007

KYB or kyobo.. cant remem the bloody name got certain gas shocks available which really does a good job on most vehicles.. there are shocks which are also adjustable to go so that ya could set ya preference and let the shocks do the rest..

depends on how well ya shocks could handle.. just a question. n00b stuff.. is the springs combined with the shocks? cuz i hear of certain ppl cutting their springs abit to lower da car n stuff..

Zz

Devinda_Z · February 12, 2007

neXGen said:
is the springs combined with the shocks? cuz i hear of certain ppl cutting their springs abit to lower da car n stuff..

its two seperate components bro

this is jus local improvisation - rather than changing to shorter springs or stiffer sports springs ppl literally CUT the coils so that there's less travel and its shorter so that makes the vehicle sit lower...logicall this would mean added strain on the shocks if they're stock right cuz it would be constandly moderately depressed né ?

ah yeah KYB is decent - they have OEM parts ofr virtually all jap specs

neXGen · February 12, 2007

hmm.. 2 seperate components ? would that mean when changing the shocks.. the springs gotta be changed too or would a pair of shocks include the springs? this got me confused..

the springs on me rear wheels could be moved up n down with just a simple touch.. so planning on attending to it soon.. was just wondering whether springs or shocks were to be bought seperately..

Zz

Devinda_Z · February 12, 2007

u dont have to change springs bro

its NOT something that u USUALLY have to change....if moves as u say it does then it deffa needs attention...

have someone like P*t St*p , Am*la or N*l*ka test é shocks

normally on the shocks would need replacing due to general wear n tear..

neXGen · February 12, 2007

Devinda_Z said:

u dont have to change springs bro

its NOT something that u USUALLY have to change....if moves as u say it does then it deffa needs attention...

have someone like P*t St*p , Am*la or N*l*ka test é shocks

normally on the shocks would need replacing due to general wear n tear..

guess in ma case.. its a red mandatory alert.. had a trip to kandy n me bloodh header 2-1 section got scratched over the slightest bumps.. and i had to move around really slow due to the smooth roads in the outskirts of kandy.. 99750 kmz on da clock without a change of shocks would give ya an idea yeah? ;-) lolz..

Zz

Devinda_Z · February 12, 2007

Oi....ur waaay over due brother!!!!!! change it!!

here ur a mära guy no---changes exhust manifold but not é shocks!!! anéy bung

your shock mounts will also probably need replacing as well as the rubber stoppers

having a good uspension set up changes your drive dynamics drastically...get it done ASAP machan...

neXGen · February 13, 2007

Devinda_Z said:

Oi....ur waaay over due brother!!!!!! change it!!

here ur a mära guy no---changes exhust manifold but not é shocks!!! anéy bung

your shock mounts will also probably need replacing as well as the rubber stoppers

having a good uspension set up changes your drive dynamics drastically...get it done ASAP machan...

hehe.. wut to do buddy.. i kept telling me dad the times come kiyala.. and it keeps on getting postponed.. i do what i could to mod the car while dad does stuff to maintain it ;-) kinda like a team effort yo! lol

somehow gotta get the suspension done with KYB stuff.. n increase the ride height a bit hopefully.. approx how much d ya assume da total costs come to eh?

Zz

Devinda_Z · February 13, 2007

shocks should be around 4k per piece i'm guessing but no idea abt é coils

what u can do is probably get é coils from one of these parts joints cuz they have mildy used cut up bits that are cheap and are pretty much original....

i maybe running abt sourcing some parts me self - so i'll keep an eye out for ur coils n shocks

neXGen · February 13, 2007

Devinda_Z said:

shocks should be around 4k per piece i'm guessing but no idea abt é coils

what u can do is probably get é coils from one of these parts joints cuz they have mildy used cut up bits that are cheap and are pretty much original....

i maybe running abt sourcing some parts me self - so i'll keep an eye out for ur coils n shocks

eh.. now i am def getting confused.. that means i ve gotta buy the shock and the coils seperately eh? wel frankly i would be looking at a bit of a sportier type of suspension (though nothing revolutionary) to smoothen up the ride and hopefully give a lil more steadiness while cornering.. that is until i get to the suspension as a whole.. ya 5afe running on stock alloys ?

Zz

Devinda_Z · February 13, 2007

its sold seperately machang

well changing to newer coild would ensure a slightly firmer feel when cornering etc but i woudnt go in for "sports" suspension - cuz having a stiffer ride on already gutten roads means ur setting yourself up for a very uncomfortable bumpy n rigid ride

lokuputhaa · March 16, 2007

Hey guys, thought this might be a good read for those who want to do tire/wheel and other suspension mods.

I recently acquired a High-Performance Handling Handbook by Motorbooks Workshop by Don Alexander...and guess what...they have a feature on how to modify a CB7 and in it they talk about how well CB7's react to specifically suspension mods.

So I thought i'd scan it and post it up so everyone can read. Another one for the CB7's !!!

btw here's the book info:

Book Series: Motorbooks Workshop

Title: High-Performance Handling Handbook

Author: Don Alexander

Published date: 2002

ISBN-13: 978-0-7603-0948-3

ISBN-10: 0-7603-0948-5

yeah the pics are going to be big; dial-up ppl be careful ur modem might explode:lol:

read on: :tu:

question: is this CB7 a member of this site?...anyone know of this car?...its worth a shot.

:thumbsup:

TurboSeavy · March 25, 2007

This is one interesting discussion, Thanks to Hola for starting this thread.

I got the car with 15" alloys and 185/55 falcon tire set. The low profiles had really hard side wall and the ride was a little bumpy. In the last tire change I swapped the front tires to 205/60/15R s. And I immediately noticed the difference in ride smoothness. One other thing I noticed is that the 60s have softer side wall so they are much more vulnerable to damage (well… I have abused the low profiles many times but they withstood all that punishment). I guess, not only the balloon size of the tire, but also the width of the tire is very important to the smoothness of the ride, as SL highways are much like off-road death pits. Fat tires increase the drag a little bit and burn a few rupees worth of gasoline more, but they give better traction, better handling/breaking and better comfort.

I still have the old 55s in the rear and hoping to change them to 60s soon.

Edited March 25, 2007 by TurboSeavy

Hola · March 25, 2007

TurboSeavy said:

This is one interesting discussion, Thanks to Hola for starting this thread.

I got the car with 15" alloys and 185/55 falcon tire set. The low profiles had really hard side wall and the ride was a little bumpy. In the last tire change I swapped the front tires to 205/60/15R s. And I immediately noticed the difference in ride smoothness. One other thing I noticed is that the 60s have softer side wall so they are much more vulnerable to damage (well… I have abused the low profiles many times but they withstood all that punishment). I guess, not only the balloon size of the tire, but also the width of the tire is very important to the smoothness of the ride, as SL highways are much like off-road death pits. Fat tires increase the drag a little bit and burn a few rupees worth of gasoline more, but they give better traction, better handling/breaking and better comfort.

I still have the old 55s in the rear and hoping to change them to 60s soon.

Im running n 55s and im quiet happy about it bro. But 60s would be more comfy but in terms of looks then its lost.