Alloy Wheel, Another Question?

[kalover]

Hi,

 

I am not sure if i should had put this in my last post about alloy wheels but thought make a new one.

 

Rite here we go again lol .....

 

My current wheel/tyres are 165/65R/13 T77

 

I want to go from 13 inch to 15 :13:

 

But .....

 

Will a 15" fit a Ford KA, as in enough room in wheel arch etc?

 

and will i have to alter the car in anyway to put a 15" on the car?

 

This is the bit i am confused about ...

 

from a website it says:

 

do the following when increasing wheel/tyre by 1"

 

Increase the tyre section width by 20mm

Decrease the tyre aspect ratio by 20 points

Increase the wheel rim diameter by 2 inches

 

So to go from 13" to 15" i would need 205/05R/15? i dont think that is rite as i can find a 205 but the ratio reducing it by 40 points would leave it with 05 and i cant find any which is 205/05/15.

 

Can someone really help me and explain it and tell me if i went for 15" what i would need as i dont want to put anything on there that will require modification to my KA and make road handling poor as ford offset what ever that is, is offset 36 and most of them are more than 36 which i read online increasing the offset can cause car handling problems specially in wet/winder conditions.

 

If someone could tell me the exact size etc for 14" and 15" as not decided yet which would look better and that will be a great help for me to go and buy, my brothers reckon see that 13 inch is crap and i should go for 15" but i dont trust everything they say so wanted to check and see what you think would look better :13:

 

 

Thank you,

M. Russell

[mk2vr6]

maths is not your strong point

[kalover]

LOL.

 

My maths is good thank you just not when it comes to cars.

 

The information i got from a website says:

 

do the following when increasing wheel/tyre by 1"

 

Increase the tyre section width by 10mm

Decrease the tyre aspect ratio by 10 points

Increase the wheel rim diameter by 1 inches

 

my size is 165/65R/13 T77

 

now if i go for 14" example it tells me to increae width by 10mm which means from 165 to 175, then decrease ratio by 10points which for me would be from 65R to 55R and add 1 inch to make 14 inch

 

is that correct? sorry the last one i increased for a 15" not 14" if you get me, my mistake.

Edited September 6, 2008 by kalover

[malcolm.dobell]

the rule of thumb you quote should lead you to 185x45/15 which don't apparently exist

 

there are two things you need to ensure:

 

1) the overall diameter of the tyre on the bigger rim is the same as that on the smaller one. - you can be bigger or smaller, but it might not fit and it will mess up the speedo calibration

2) if you use a wider tyre, then there's a risk of contact with the wheel arch on full lock.

 

the tyre size has three components:

 

width, in mm

aspect ratio in %

and rim diameter in inches.

 

they couldn't really design it to be more compicated if they tried!

 

so your 165/65/13 tyres have a wall height of 65% of 165 which is 107mm. double this for the overall height - 214mm and convert to inches: - 8.5inches - total with the rims of 21.5inches.

 

your new tyres/wheels have to be the same diameter, so if you want 15 inch wheels you have 6.5 inches for the tyre thickness. Halve it an convert back to mm - comes to 82.5mm; you'd probably want 45% section tyres - you could use 195x45/15 which are a bit over-sized (87.5mm - 10mm over on diameter, and your speedo would read under your actual speed by 4% compared with where you are now.

 

if you buy tyres 30mm wider than you currently have you really must check there's clearance to the wheel arch on full lock and with the wheels/offset you use there's clearance between tyre and the suspension strut. BUT - government health warning coming - - I have never done any of this!!! also you must tell your insurer!!!

[kalover]

Hi,

 

Thanks, very complicating stuff i must say.

 

Well i have decided to go for a 14" as it is not to big and i hope and should think it wont casue a problem.

 

Majority of websites using there search recommend if i go for 14" would be 165/60/14

 

Does that sound ok? I mean do you think there will be any problems as i am only going up 1 inch in size from 13" to 14"? (from 165/65R/13 to 165/60R/14)

 

Also what do you reckon of these (LINK) , Are they good make such as quality? as i read that some buckle very easily. Also if you scroll down it will show you how it looks on a KA, do you think it suits the KA?

 

Thank you,

KaLover

Edited September 7, 2008 by kalover

[malcolm.dobell]

My suspicion is that you'd barely notice the difference between 13" and 14"!

 

the tyre size seems more a matter of "no choice" than any other consideration. the wheels +tyres would be about 10mm bigger in overall diameter and like in my previous reply you'll go slightly faster for a given speedometer indicated speed.

 

good luck