Kuat

i'm planning to increase tire profile from 17/50 to 17/55

do you think this could have a negative effect on anything ?

(i'm doing this to get a slightly softer ride, the roads aren't too good here)

Bteljuice

wht wheels do u have? yes it would affect as the overall diameter will change. your tire will become wider then the wheel giving you an uncomforting ride. ur also probably getting a harsh ride because 17/250 isnt the proper tire for your 17s.

Kuat

shit i got it all wrong,

i meant 17/50 to 17/55

the tire 'hight'

Bteljuice

loooool. still, it'll change the overall circumference(i said diameter before ). the ride will become smoother BUT, since your roads aren't so good, bumpy, you'll probably will getting some rubbing everytime you hit big potholes. GL

seoulman

Since the total diameter of your wheel/tire combination will increase, the accuracy of the speedometer will change. Your ride will also become slightly softer, but I doubt this will be a noticeable change. I believe that most experts will tell you to stay within 5% of the original wheel/tire diameter. If going to a 17" 55 series profile is within that 5%, then you have nothing to worry about in terms of damage to your car. If it is greater the 5%, stick to your 17" 50 series profile.

pinguhk

the speedo will be wrong too

Jambers

As stated above, the speedo accuracy will change slightly so just watch them speed camera's LOL

The only other thing to consider is that if you have Run Flats, you could may be consider standard tyres of the ize you have now. That I think will probably make a greater difference to ride comfort than just increasing the height a tad.

Bteljuice

+1 for non-run flat. And as soulman said, if you exceed 5%, then your tire will rub

pennetta

The 17 is the rim size, you don't list the tire width size and the 55 is calculated off of that- meaning that the sidewall is 55% of the treads width or 50% of the tread width. So the higher you go the taller the sidewall will be. If you have 225 mm width then 50% is 112.5 mm and 55% is 123.5 mm, remember that those numbers are doubled because the side walls (top and bottom) plus the rim size gives you the diameter. Pi 3.14 times the diameter gives you the circumference and also the rotational distance with one complete revolution of the wheel. 17" = 431.8 mm

50 Series = 2(112.5) + 431.8 = 656.8
pi 3.14 x 656.8 = 2064.23 circumference

55 Series = 2(123.5) + 431.8 = 678.8
pi 3.14 x 678.8 = 2133.37 circumference

So speedometer error with be 3.3% so 55 mph will now actually be 56.8 mph and overall increase in tire height would be 22 mm or about 7/8". Tire width does not change.

luigi524td

If you're so inclined try this tire/wheel configure tool:
http://www.racewerks.net/link1.htm