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Discussion Starter · #1 ·
Wherever I look I find that the tyre size for the E-Pace are :
245/45R20
245/45R21

Isn't that odd ?
How could they both have 11cm sidewalls..

The 21 wheels with tyres on are obviously bigger so how could the speed parameter etc.. be correctly displayed ?

It would also mean that the comfort is the same with the same sidewall's height

What am I not getting ?
 

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Isn't it that the 245 is the width of the tyre, the 45 means the sidewall is 45% of that (the 11cm) but the R20 or R21 is the diameter which has nothing to do with the first two measurements. You could have a tiny R4 Tesco trolley wheel with an 11cm sidewall (it would be a large thing I admit) or an R60 tractor wheel with an 11cm sidewall.
 

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Discussion Starter · #3 ·
You're right but the wheel's diameter = rim size + tyre sidewall and I thought that it should always be the same value for one car.

What I mean is the bigger rim the smaller the tyre sidewall to ensure that the diameter stay the same (+/-3%).

One inch is probably not an issue for the ESC, speed etc.. anyway my reasonment must be flawed somewhere :)
 

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In my eyes you are correct 'shadow', the sidewall height remains at 110mm but the overall diameter of the wheel and tyre is increased by 25mm. There will be a difference in the speedometer, but by how much I don't know and whether with such a small aspect ratio height if it really matters, as it's really only a little more in the difference between a new tyre with 8mm tread (which in this calculation will be 16mm) and a worn one.
 

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Discussion Starter · #5 ·
I didn't think of that ! Thanks, now you can help me out with my driving in snow conditions issue (on Jaguar Customer Relations) :D
 

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my head hurts now...!
 

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a quick internet search suggests the 20 or 21 is the diameter of the rim only ie. not the rim plus sidewall (x2)
 

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Discussion Starter · #10 ·
Thanks (yes the 20inch is the diameter of the rim but with the same tyre sidewall the total diameter of the wheel cannot be the same between the 2).

With your website we can clearly see that there's a 3,49% difference and that at 70mph you'll really be driving at 73,49mph with the 21inch rims.
 

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Discussion Starter · #11 ·
And.. I've got 235/50R20 tyres on the 2021 model = 117,5 sidewall
 
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