17 rim tyres

[Crymson]

I have a question and I hope to get some answers from those who know. Most people using 17 rims would be using 215/45/17 or 225/45/17 tyres as the recommended maximum difference in diameters should be +-2.5% from standard 15'. Using www.miata.net/garage/tirecalc.html, you can see that using the 215/45/17 would have a speedo reading with non-stock tire at -0.3%, ie speedo would read 60 mph but actually travelling at 59.8 mph. Using 225/45/17 would have a speedo reading with non-stock tire at 1.2%, ie speedo would read 60 mph but actually travelling at 60.7 mph. But I would like to know if anyone is using 215/50/17. and what are your opinion & conclusion in using this size? The tyre size calculator would read a 3.2%, which is above the +-2.5% rule. Meaning, when your speedo says you are travelling at 60 mph, you area actually travelling at 61.9 mph. Just toying with the idea of getting thicker tyre size. Low profiles are constantly being damage by our bad road conditions daily.

 

[seech]

crymson, at the moment you're assuming that your speedo on the ori tires is accurate. Stock speedos all overread your actual speed, mostly by 5-10kmh over. ie. if the speedo indicates 110kmh, usually the car is only travelling at 100-105kmh.

Better you calibrate your speedo yourself. Drive on a highway at a constant speed and time how long it takes to cover 1km. 120kmh=30sec. 110kmh=32.7sec. 90kmh=40sec. 60kmh=60sec. At least then you have a better idea of the approximate 'actual' speed of the car and can then make adjustments to your tire size to get the reading you want.

 

[Crymson]

seech

thanks for the reply. But I would like to know other forummers opinion and experience in using 215/50/17 instead of 215/45/17. Any disadvantage. Just want to protect my rim from pothole damage by having a thicker tyre.

 

[absidian]

As they say, "do the maths" and you'll know the answer.

215/45/17 diameter 625mm circumference 1964mm
215/50/17 647mm 2032mm
Difference: diameter 21.5mm, circumference 67.5mm
About 3.44% difference.

So, your speedo will read 70mph (112.7kmph) when you're travelling 72.4mph (116.5kmph).


Incidentally, the 328s and M3s take 225/45/17 which is a closer match (1.44% difference) and is also a more common size to find/buy.


Hope this was useful. Enjoy making your conclusion

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[Crymson]

alright then. i guess there is no point going for 50 then. thanks.

 

[machaplai]

all my brother, do u all know wat price for falken ze522 .......225x45x17. tq very much

 

[Mouse]

all my brother, do u all know wat price for falken ze522 .......225x45x17. tq very much

klang jalan kapar, tyre shop beside caltex, with barum & maxisss signboard selling around 250-260, cheapest u can get anywhere