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View Full Version : Common tyre misconception


1-JAY-Z
13-09-10, 13:09
Some of you may know this for those who dont have a read. I was asked about a tyre size on AE86irl and thought it might be beneficial to some here who dont know.

The size in question, 175/50R14

A common mistake when reading tyre sizes is people think the profile (175/ 50 R14) is in MM's, its NOT. In this case 175 means its 175mm's in width, The 50 part is its aspect ratio meaning the sidewall is 50% in height compared to the width so that means the sidewall in MM's is 87.5mm high (175mm/2 = 87.5mm) and lastly the 14 is obviously in inches. If you were to write it in MM it would look like 175mm/87.5mm/14"

Moral of the story is going for a lower profile dosnt always neccesarly mean your getting a tyre with a lower wall. It's not the case all the time but worth thinking about the next time your changing your tyres due to not liking the wall profile they have.


Edit: could someone fix the heading typo please.
PeterT
13-09-10, 14:58
Yep, good post, people always get this wrong!

edited title too
1-JAY-Z
13-09-10, 15:00
Yep, good post, people always get this wrong!

edited title too

Thanks!!!!
s13-ste
13-09-10, 15:10
and the new thing i learned today is..............................................^^ ^^^^up there.

i always thought it was mm.
Rob32
13-09-10, 15:27
People always think the R in the tire size means its radius is 14inches as its normally put like 17565R14 the R actually denotes that its a radial tire as opposed to the old fashioned cross-plys
pole drift
13-09-10, 15:27
so would the tyre fit on the rim if your fittin a tyre wit a smaller tyre wall e.g going from 205/50 R17 to 205/40 R17???
200sx
13-09-10, 15:31
[QUOTE=pole drift;163857]so would the tyre fit on the rim if your fittin a tyre wit a smaller tyre wall e.g going from 205/50 R17 to 205/40 R17???[/QUO yes cause your still stay with a 205...your only increaseing or decreaseing the tyre wall size,you could put on prity much any size tyre wall you want,its when the width off the tyre changes thats when you could run into problems!!!
1-JAY-Z
13-09-10, 15:38
People always think the R in the tire size means its radius is 14inches as its normally put like 17565R14 the R actually denotes that its a radial tire as opposed to the old fashioned cross-plys

Correct......
Keli
13-09-10, 17:55
God this is a terribly interesting thread!
Prodrifter86
13-09-10, 18:03
this is some good info right here!
1-JAY-Z
13-09-10, 18:07
God this is a terribly interesting thread!

Do I detect some sarcasm? Or am I just been a moody bollix?
Scamper
13-09-10, 18:08
Thats somet new i learned now, i didnt know that, thanks for that
Rob32
15-09-10, 11:21
Correct......

I know im one of very few people qualifed in tire fitting and construction :D