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My car comes stock with 195/55/15 and I was wondering if it's illegal to change the profile of the tyre of the same size? The dude from Bob Jane told me I had to stick with the same profile...
The tyre I was wanting to put on are 215/45/15. Will this pass roadworthy/VicRoads?
will pass with flying colors, its more to do with rim size rather than tire profile
Only problem I can see is your rolling diameter would be slightly smaller which would put your speedo out but I'm not sure if that's enough to be a legal issue
I think 215/50/15 would be better if you can get it
^^^ What he said.
195/55/15 wall height is 107mm
215/45/15 wall height is 97mm
215/50/15 wall height is 107mm
I read somewhere that the whole diameter cannot be more than 15mm out... can anybody clairfy?
In Victoria, the rolling diameter has to be within 12mm of the factory specs either way (bigger or smaller) To be legal.
Yeah i've read that, i'm a lil confused about that 15mm diameter rule which I think applies to this case...
Yep it definitely applies.
With the 195/55/15 you have now, your diameter is 595mm
With the 205/45/15 it would be 574.5mm so the difference is more than 15mm which is where your problem is
Thanks for clarifying that. What's the formula for your calculations?
Convert rim size to millimetres = 15 x 25.4
Tyre Wall Height = width x profile
Rolling Diameter = rim size + 2 x wall height
Thanks a lot! It's Maths all over again!
No worries mate. Glad I could help
How much does this actually affect your speedo?
Depends on how big the difference in tyre size is
In the sizes the OP was talking about 205/45/15 is 5% smaller than 195/55/15 so the speedo will read 5% too fast
Just use this will give you all the answers...
http://www.1010tires.com/tiresizecalculator.asp