Upsizing rolling diameter

[Zyrofillica]

Hi guys,

 

Thinking of upsizing from 205/55/16 to either 225/50/17 or 225/45/18

 

difference will be new tyre is 5% larger than original in terms of diameter. Has anyone upsized their tyres this way and how did it affect your car?

 

My body kit is too low and my wheel gap is too large so instead of lowering it i am thinking make the wheel bigger to cover the gap and at the same time preserve the ride height so i may still enter MSCP.

 

My wheel gap is 3 inch. my front kit to ground is 3 inch which is already scrapping every mscp in singapore.

[Mecontle]

only problem is ur speedo reads lower speed than actual , but the real problem is ur fencer may get grinded off

[Jonjees]

with wider tyres, you will find that the steering feel will differ.

as well as the handling during corners, since there is a larger contact patch now.

 

but you might want to check if your ride can fit the 50 and 45 profiles with the 17" or 18"

also depending on the offsets, you might have to roll your fenders.

 

the weight will also affect FC, unless you get some lightweight forged rims.

but the bigger rims always looks nicer :)

[Beregond]

if u change your tyre diameter , different in actual speed reading, hitting the fenders is only the minor problem that might happen,

 

different in speed reading confirm.

hitting fender depend on cars.

 

the worst case sitution is the auto gear shifting malufuction. some conti car, or high end performance using semi auto gear.

will not up/down shift properly if the actual speed is different.

i haven encounter before. but heard before a few cases , best to check with the pro before u do it lol.

[Zyrofillica]

if u change your tyre diameter , different in actual speed reading, hitting the fenders is only the minor problem that might happen,

 

different in speed reading confirm.

hitting fender depend on cars.

 

the worst case sitution is the auto gear shifting malufuction. some conti car, or high end performance using semi auto gear.

will not up/down shift properly if the actual speed is different.

i haven encounter before. but heard before a few cases , best to check with the pro before u do it lol.

 

good point. did not think of this aspect. is 4% difference alot? anyone here has ever upsized their tyres?

 

my fender definitely wont tio, cos now my car looks like its on stilts and has got chicken legs.

 

Finding a way to reduce the wheel arch gap and at the same time preserve my bumper clearance. Anyway to do this other than upsizing tyres?

[Mecontle]

if u change your tyre diameter , different in actual speed reading, hitting the fenders is only the minor problem that might happen,

 

different in speed reading confirm.

hitting fender depend on cars.

 

the worst case sitution is the auto gear shifting malufuction. some conti car, or high end performance using semi auto gear.

will not up/down shift properly if the actual speed is different.

i haven encounter before. but heard before a few cases , best to check with the pro before u do it lol.

 

tranny doesnt care what is ur OD, but only rim & tyre weights & is easy to rectify given lighter rims compared to speedo error calibration

 

too heavy unsprung , ur torque convertor / clutch will smoke in no time

 

[Mecontle]

Finding a way to reduce the wheel arch gap and at the same time preserve my bumper clearance. Anyway to do this other than upsizing tyres?

 

spring lowering

[Furrynadz]

225/45/17, 205/50/17

 

 

[Fcw75]

Have you used this to calculate the difference in measurement?

 

http://www.miata.net/garage/tirecalc.html

[Zyrofillica]

Have you used this to calculate the difference in measurement?

 

http://www.miata.net/garage/tirecalc.html

 

i have. 4.4% bigger is that too much?

 

[Zyrofillica]

tranny doesnt care what is ur OD, but only rim & tyre weights & is easy to rectify given lighter rims compared to speedo error calibration

 

too heavy unsprung , ur torque convertor / clutch will smoke in no time

 

huh? so wat about if car is always fully laden, my torque convertor also will smoke?

[Prodrive7354]

good point. did not think of this aspect. is 4% difference alot? anyone here has ever upsized their tyres?

 

my fender definitely wont tio, cos now my car looks like its on stilts and has got chicken legs.

 

Finding a way to reduce the wheel arch gap and at the same time preserve my bumper clearance. Anyway to do this other than upsizing tyres?

 

Hi

 

I have the same thinking as you. Upsize the tyres to reduce the wheel arch gap and bodykit issue. After getting alot of negative comments from some of the forums. Finally I still decided to give it a try cos I ready can't stand big wheel arch with small tyres. Anyway I'm driving a Kia Rio HB auto.

 

Currently my ride is 4% difference. From 205X45X16 upsize to 205X45X17 instead of 205X40X17. Speedo reading compare to my Garmin GPS is slightly off by 1%. Beside that, you will feel your car sightly higher then before. Like mini clubman..

 

Some of things you may want to take note. 1) FC will suffer partly becos 17" 2) Pick up wise to me same as before when I'm on 16". 3) Braking distance slightly affected maybe becos is car heavy then before. 4) Tranny changing gear feel the same. But recently got some prob during shifting but this issue already appear when I'm on 16".

 

Other then the abovementioned so far so good. Oh ya I have tried full load with 5 adults on board the tyres never hit the fender but instead look veri chio cos the wheel arch got no gap. Finger also cannot insert in.

 

Hope this will help you to decide what you want.

Edited September 26, 2011 by Prodrive7354

[Hiaceminibus]

I have a question. i Know that many Japanese car speed sensor is install inside the gearbox, y the change of the tire size will affect the actual speed travel?

[Fcw75]

Seems too much to me. I read a website and it says the maximum should be +/- 2.5%.

 

http://www.etyres.co.uk/tyre-size-calculator.htm

[Zyrofillica]

your car lowered on coilovers?

[ER-3682]

your car lowered on coilovers?

what car are you driving.?Our speedometer by the way is about 5-7% faster,actually upsizing your tires will make it more accurate.

[Chucky2007]

Inaccurate odo is small issue.. its the rubbing with fender when making completed turn that's irritating. . Make sure yr wheel arc can accommodate. I upsize 3%.. more for comfort factor as thicker.. having the tyre svrabbing against fender when turning completely when doing u turn especially

[Tayspiderx]

best if you can share your concern with the same car model fan club so they can provide the most accurate live data.