tyre sizes

[markii]

if im on 205/65/15 tyres can i change it to 225/60/15. what are the effects?

 

[trex92]

since 205 and 225 measures the width of the tyres and 65 and 60 measures the thickness of the tyres (in %), using a 205/65 means that from the rim is 133.25mm (205mm x 65%) whereas 225/60 would be 135mm so by changing to the 225, u would actually be running on slightly bigger wheels (bigger by 1.75mm).

Bigger wheels usually means that:-

1. Slower acceleration due to heavier wheels and bigger circumference of the tyre (think of a bicycle, bicycle with small wheels against bicycle with big wheels, which would be able to move first with the same energy pedalled?).

2. Higher top end speed as now 1 revolution of the bigger wheel would mean greater distance covered (since bigger circumference).

3. Bigger wheels would cause ur speedometer to be slightly out of syn and give a wrong reading.

Since the difference isnt that big, ie 1.75mm, the differences might not be noticable.

 

[markii]

so i cannot put the 225/60/15 tyres on my current wheels which are wrapped in 205/65/15 tyres?

 

[prodigy]

A point to note is the offset of the wheels and whether your car can take the extra width of the tyre. You wouldn't want to hear the tyre scraping against the top of the arch everytime you go over a bumpy stretch or when you're carrying a few fellas.

 

[RedD]

3. Bigger wheels would cause ur speedometer to be slightly out of syn and give a wrong reading.

Since the difference isnt that big, ie 1.75mm, the differences might not be noticable.

so..if change to a bigger rim o tyre... nit set back the rpm???

 

[trex92]

so..if change to a bigger rim o tyre... nit set back the rpm???

RPM is based on the revolution of the engine and has nothing to do with the wheels. Can say RPM is the speed of the engine. So RPM would not be affected.

As mentioned, the new tyres although bigger, it is not a big difference, the factors that i mentioned is not big issue. prodigy, is right, using 225 too means that ur tyres are wider so dunno whether ur tyres would then scrap the sides especially for the front wheels when u turn the steering. I forgot to add one more thing also too, wider tyres would mean more surface area of tyre grip, so the tyre traction would be better.

 

[botak_hensem]

RPM is based on the revolution of the engine and has nothing to do with the wheels. Can say RPM is the speed of the engine. So RPM would not be affected.

As mentioned, the new tyres although bigger, it is not a big difference, the factors that i mentioned is not big issue. prodigy, is right, using 225 too means that ur tyres are wider so dunno whether ur tyres would then scrap the sides especially for the front wheels when u turn the steering. I forgot to add one more thing also too, wider tyres would mean more surface area of tyre grip, so the tyre traction would be better.

i just change my tyre from 165/60/13 to 215/17/45, the speedometer must resetting or not? you said is true, my car run much slower than usual but the traction is very good, no scrap oso when i used 225/17/45, but i want to know whether there a much different in my standard speedometer?
if i used rsm or kind of digital meter, does it more accurate?

 

[markii]

hmm good question... i also wanna know the oem digital speedo affected as well or not?

 

[trex92]

i just change my tyre from 165/60/13 to 215/17/45, the speedometer must resetting or not? you said is true, my car run much slower than usual but the traction is very good, no scrap oso when i used 225/17/45, but i want to know whether there a much different in my standard speedometer?
if i used rsm or kind of digital meter, does it more accurate?

165/60/13 = 165mm x 60% + 381mm (rim size)/2 = 289.50mm radius from center of rim

217/45/17 = 217mm x 45% + 431.80mm/2 = 313.55mm radius from center of rim

Clear difference of 24.05mm ie 2cm bigger radius which translate into about 15.113cm bigger circumference (circumference = 2 x radius x pi). Means now for every full revolution of ur tyre, ur tyre now needs to travel 15.113cm more than compared to previously. Your speedometer reading would be out for sure but question is how much. Last time say 100m, on ur old tyres, ur wheel spun 54.97 times whereas new wheels spun 50.75 times, roughly would translate to about 92% lower speedometer reading now...

I am not sure how RSM and digital speedometer takes its reading as it is definitely not mechanical means such as proton's speedometer. But I think it would be out too, but since it is digital and that it is supposed to be installed in any car, this should mean that u should be able to set the digital speedometer easily....

 

[botak_hensem]

165/60/13 = 165mm x 60% + 381mm (rim size)/2 = 289.50mm radius from center of rim

217/45/17 = 217mm x 45% + 431.80mm/2 = 313.55mm radius from center of rim

Clear difference of 24.05mm ie 2cm bigger radius which translate into about 15.113cm bigger circumference (circumference = 2 x radius x pi). Means now for every full revolution of ur tyre, ur tyre now needs to travel 15.113cm more than compared to previously. Your speedometer reading would be out for sure but question is how much. Last time say 100m, on ur old tyres, ur wheel spun 54.97 times whereas new wheels spun 50.75 times, roughly would translate to about 92% lower speedometer reading now...

I am not sure how RSM and digital speedometer takes its reading as it is definitely not mechanical means such as proton's speedometer. But I think it would be out too, but since it is digital and that it is supposed to be installed in any car, this should mean that u should be able to set the digital speedometer easily....

thats means if my speedometer show 92km/j, it means the actual speed for my car is 100km/j right? so i must reset the old setting of the speedometer and set new setting? i jus cant do an equation between the diameter tyres and the speed, can u show me the formula between the diameter tyre and the speed?thanks bro, u'r really clever la....

 

[evo5229]

helooo all sifu..

im driving waja ....so i would like to change to 16" i like 17" laaa

but i dowan lower my car...so if u is nipis means 50...it will ugly and 5 finger can go in.....and the car is high rite??

so izit i can go for 205/60/R16......so that i nonit lower and the rim look nipic also rite,.....


haih..i also dono la......dowan 5 fingers go in but i want tyre nipis and nice....

dono how...HELPSAAA thab[nksss

 

[trex92]

thats means if my speedometer show 92km/j, it means the actual speed for my car is 100km/j right? so i must reset the old setting of the speedometer and set new setting? i jus cant do an equation between the diameter tyres and the speed, can u show me the formula between the diameter tyre and the speed?thanks bro, u'r really clever la....

my 92% is a rough estimate from current revolution for 100m divided by previous revolution for 100m. Since the speedometer works is by mechanical cable (for proton at least). This mechanical cable would be spinning when the car is moving. This cable spinning is directly related to the wheel revolution. And for speedometer console to register speed, it might be tuned that 60 spins of the cable = 1 km. If you open up ur speedometer console, behind the meter u would see the specs for how many spins = 1 km. I forgot the actual number, think it was 67 or 87. So like i said, since the cable spinning affects the speedometer and the cable is directly related to the wheel revolution, so in theory, a % change in the number of revolution due to bigger/smaller tyre should give the same % change in the cables spinning and hence same % difference in speed reading...