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+--- Forum: Wheels & Tyres (https://www.japcarforum.com/forumdisplay.php?fid=152)
+--- Thread: tyre size help (/showthread.php?tid=8977)
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tyre size help - Lexuspat - 15-09-2019
hi all,
i have been offered a set of tyres for nothing from a mate but not sure if they would fit my standard 17" lexus alloy wheel
i have on the car 215/45/17 and these are 215/40/17 would this make any difference and would they be ok on the rim
please help i useless when it comes to tyres
tyre size help - SHAHZ - 15-09-2019
the number 40 is the sidewall profile mate, so it will be 5mm lower than the 45 you currently have, will fit, just means a slightly harsher ride! but that is well and truley compensated for when they are free
tyre size help - Lexuspat - 15-09-2019
thanks Shahz like i said im useless with tyre info lol
tyre size help - Stoney - 15-09-2019
Will fit just on the wheels perfectly mate.
On the plus side, you will have a slightly lower, though slightly harsher ride, and this should boost both handling and acceleration a tiny bit. On the downside, the tyres may look a bit skinny and the overall wheel size may look too small, your speedo will read under a couple of percent and top speed will drop marginally.
Info for you below:
(The forum always murders table formatting! The first figure is for the stock tyre and the second figure for your proposed new one, for each respective aspect.)
Diameter: 625.3mm 603.8mm
Circumference: 1964.4mm 1896.9mm
Speedo error: 0% 3.56%
Reading at 30mph: 30mph 31.07mph
Reading at 60mph: 60mph 62.14mph
Ride height loss: 0mm 10.75mm
Arch gap increase: 0mm 10.75mm
tyre size help - Stoney - 15-09-2019
SHAHZ the number 40 is the sidewall profile mate, so it will be 5mm lower than the 45 you currently have, will fit, just means a slightly harsher ride! but that is well and truley compensated for when they are free
You are right that the second number is height, but it is not in mm. It is as a percentage of the width. So 215/45/17 is 215mm wide on a 17" rim, but the sidewall height is 215mm x 45% = 96.75mm. 215/40/17 is 215mm wide on a 17" rim but with a sidewall height of 215mm x 40% = 86mm. A difference in this case of 10.75mm. This is each side, so overall the wheels will be 21.5mm smaller in diameter, though only 10.75mm difference in ride height, seeing as only the half of the wheel below the axle effects the height of the car, the other 10.75mm difference is in the extended gap between the top of the tyre and the arch.
Effectively; the car will drive like it's been lowered 1cm, but look like it's been raised 1cm!
tyre size help - FirebirdPhil - 15-09-2019
SHAHZ the number 40 is the sidewall profile mate, so it will be 5mm lower than the 45 you currently have, will fit, just means a slightly harsher ride! but that is well and truley compensated for when they are free
No side wall it a percentage of the tyre width.
tyre size help - Lexuspat - 15-09-2019
thanks for all the info on what is what regarding tyres.
and im happy that they will fit so ill be sorting these out soon before the weather gets any worse
tyre size help - Stoney - 15-09-2019
2tongues No side wall it a percentage of the tyre width.
Is there an echo in here?
tyre size help - FirebirdPhil - 15-09-2019
Stoney Is there an echo in here?
I missed your post as I just hit quote without reading the thread - I do that its big and clever:whistling:
tyre size help - jay_russell - 15-09-2019
it's so crazy with tyre sizes,
the first 3 numbers are in mm ( 215)
the next 2 numbers are a % of the first
and the last 2 numbers are in inches
what a mess
and i work with this every day