Need help on tire size, going for old school look

[Lonewolf64]

225/50/16, lowered by 1.5-2" by Eibach Prokit springs. As for shocks, it has Koni Yellow racing inserts up front and KYB AGX in the back. The wheel size is 16x7.

 

[cheekychimp]

Quoting BarnesMobile:
Ummm, cheeky... the second number in tires sizes is a percentage of tire wide. So a 205/70r15 has a 10% taller sidewall than a 205/60r15. That's about 5" in rolling diameter. Thus why they look huge.



Yeah I thought something didn't add up, I've been looking at those pictures all week thinking that can't be right. So how in the hell do you actually calculate that measurement? They never taught us that in 'construction and maintenance', I guess they never figured it important as it doesn't relate to any traffic offences like load indexes and tread depth do.

If the tyre has that much more rolling diameter won't it affect the accuracy of the speedometer? I know changing the rim size on my motorcycle messed up the speedo reading completely.

 

[Barnes]

Well, thanks to America screwing up the works, the math kind sucks. But here goes for a 205/70R15 tire:

205mm wide
Sidewall height is 70% of 205mm which gives: 143.5mm OR 5.65"
So, 15" wheel + 2x 5.65" = 26.3" rolling diameter

For a 205/60R15 tire:

205mmwide
Sidwall height is 60% of 205mm, which gives: 123mm or 4.84"
so, 15" wheel + 2x 4.84" = 24.7" rolling diameter

Yes, rolling diameter affects your speedometer. The larger the diameter, the larger the circumference. The larger the circumference the fewer rotations a tire has to make to go the same distance. Therefore your speedo pick or cable shows fewer RPMs and thinks you are going slower.

 

[turbowop]

You can figure out how far off the speedo is at certain spots by using a GPS. If I recall, when doing speedo-indicated 60mph in my car, I'm really doing ~65mph. Not bad.

 

[fuel]

with the 205/60 tyres my GPS reports my speedo is just about 100% accurate.

 

[vtecds1]

Quoting Struc:
Quoting vtecds1:
Same set up as I wanted to do. Can you take a pic of the car from the back?



Not sure what you were looking for? Wheel gap maybe with the new springs / struts?






I wanted to see how wide the tires looked if someone was driving behind you.

 

[dmj]

Some pics of the wheels on the car with 225/50/16. Wheel and tire combo weighs in @35 lbs 2oz.

 

[RedTwo]

Are those superlights/minilights? I like them but wish they we could fit them with more dish/negative offset /ubbthreads/images/graemlins/idea.gif
I think someone had some 16/17" Watanabe (or similar) on their VR4 a few years back... I wish I could find that photo.

 

[dmj]

They are Rota RB's 16x8 38 mm offset lightweight about 16lbs.

 

[Struc]

Quoting vtecds1:
I wanted to see how wide the tires looked if someone was driving behind you.



Ah. Ok, how about this picture...