15 - 17Inch Problems?

[wangtastic]

Hi there,

I've purchased some 17" alloys for my 52 plate 1.4 rolla.

My question is as I have 15" alloys currently fitted will I have any problems with the 17"?

Someone at work was saying that it'll throw my speedometer off massively? :/

Any help would be massively appreciated :)

[CorollaD4D]

using 215/40/17 tyres they will not cause significant change. 'massively' is a gross exaggeration. obviously there will be some change but nothing to worry about. by the way as far as i know 215/40/17 is the standard 17" tyre size

[Rob1980]

On my Renault 5 GT Turbo, I changed the wheels from 13" to 15" wheels. I can not remember the tyre spec but the speedo was reading about 4 or 5mph slower. I hope this helps as it was also a 2" difference.

[Jamesbelfast]

No point in risking a speeding ticket and/or points on your licence.

The link below allows you to calculate differences in the rolling radius of different size of tyres and also give the percentage error, etc.:)

http://www.kouki.co.uk/utilities/visual-tyre-size-calculator

[msprince]

Im running 205/40r17, if memory serves me righti think when my speedo reads 70 im doing 67.

[wangtastic]

Oh wow! cool thanks guys! :)

That's not as bad as I thought.

Random question but will it affect my mileage counter and/or my fuel economy?

[CorollaD4D]

mileage counter no, fuel economy you won't notice

[wangtastic]

brillza! cheers mate

[madvinegar]

Since you now have 195/60/15, the best dimension you can go to is 205/45/17.

You will increase your wheel perimeter by only 0,21% which is minimal. It will not affect your speedometer and you will not notice the diferrence in fuel consumption.

Just make sure that you find a lightweight rim so as not to affect your car's acceleration and general performance either.

[wangtastic]

thanks man :)

[andycam06]

No point in risking a speeding ticket and/or points on your licence.

The link below allows you to calculate differences in the rolling radius of different size of tyres and also give the percentage error, etc.:)

http://www.kouki.co.uk/utilities/visual-tyre-size-calculator

that was a handy site, cheers james.

when my speedo reads 60 iam actually doing 63.4, i thought it would have been more as i went up 3", thats not too bad ;)

[noedel]

Hello,

My first 17" alloys also had 205/45/17 tires on, as said above, it's only 0.21% difference ;)

But i had lowered mine 50mm all round, and that rubbed at the front.

So watch out when u lower it :)

(Now i lowered it untill 4cm from the ground, using 195/40//17 tires, no more rubbing, speedo has 4.5% difference, but i don't mind :P )

Grtz

[wangtastic]

ahh see I'm planning on lowering mine by 40mm (so 4cm)!

[msprince]

Im lowered 35mm and no rubbing with the above 205/40r17

[wangtastic]

I guess there's only one way to find out...

won't be a while yet though as I gotta refurb the alloys first.

luckilyyyyy the local alloy wheel franchise is headed up by a friend of mine so should hopefully get some discounts!

[noedel]

4cm shouldn't be a problem actually.

But then I'd take 205/45 in stead of 215/40 :)

Good luck!

Grtz

[wangtastic]

OK cool! Cheers mate!

[madvinegar]

Im lowered 35mm and no rubbing with the above 205/40r17

May I ask why you chose this dimension?

Since you have a CTS, the OEM dimension is 195/55/16. By going to 205/40/17 you have a -4.04% fault which I believe is huge (everything above 2% is not recomended).

You have decreased your wheel diameter from 621mm to 596mm i.e. 25mm (2,5cm!) lower. Are you experiencing over-spinning? Not to mention that the speedometer will be very inaccurate especially in high speeds.

The best dimension for you as well is 205/45/17. The fault is just - 0,74%.

Think about it.

[msprince]

I checked it out and at 60 my speedo reads 57 so nothing im really bothered about, I prefer the look of 40's over 45's on a 205 rim.