Tyre question

[Oztrailer]

Hi guys I am still around

I need to get two new tyres for the back. It currently has 295/50/15 which were on it when I get it and look awesome I have always said when I needed new ones I would go smaller because it still occasionally scrubs the inside of the guards when I go over bumps sometimes when driving. I spoke to a tyre shop yesterday and I said I would like 275's but they said I would need to go 65 series. They said if I wanted to stay 50 series I would need 265's. I know nothing about the profiles etc so would going to 65 series or staying 50 series make any real difference? Thanks for any input.......

[JTS71 Mach1]

Oh yeah it will make a big difference in sidewall height. A little lesson on tire sizes, and what the numbers on the tire actually mean. The first number is the width of the tread section. 295 actually means 295 mm measured across the face of the tread. The second number or series ratio 50 is approximately how wide the side wall of the tire is, in relation to the tread width. 50 means 50% or half of 295mm or 147.5mm so the side wall of a 295/50 x15 would measure roughly 147.5mm from the bead to the edge of the tread. Now the same width 295/65 x 15 tire, the ratio would be 65% of the tread width. or about 177mm height of the sidewall which would give you a much larger diameter tire all together. These are approximate measurements and vary from one manufacturer to another. That is why they usually recommend same brand or matched pairs on an axle. Hope this helps. JTS 71 Mach1

[Steven Harris]

Hey Steve O!

I meant to call you a couple of weeks ago and still haven't got that done!

Here is a link to a tire calculator that I just used to translate your request.

http://tire-size-conversion.com/tire-size-calculator/

(By the way your Mach 1 has tires and they fit under fenders - that is until the 2015 model at which time they will come from the factory with tyres and guards)

Anyway your 295/50/15 tyre translates to:
Diameter - 26.6" (67.564 cm)
Width - 11.61" (29.4894 cm)
Sidewall - 5.81" (14.7574 cm)
Circumference - 83.6" (212.344 cm)
Revolutions - 758.2

A 275/65/15 would be:
Diameter - 29.1" (73.914 cm)
Width - 10.83" (27.5082 cm)
Sidewall - 7.04" (17.8816 cm)
Circumference - 91.3" (231.902 cm)
Revolutions - 694

An a 265/50/15 would be:
Diameter - 25.4" (64.516 cm)
Width - 10.43" (26.4922 cm)
Sidewall - 5.22" (13.2588 cm)
Circumference - 79.9" (202.946 cm)
Revolutions - 793.4

I think the 275 would be too big in diameter and personally I would hate to loose the width by going down to a 265. Does your current tyre rub on the inner guard or the outer guard?

[Oztrailer]

Thanks for the input.

Hi Steven, Yeah I would like to keep the same width but the tyre scrubs on the outer guard when I go over dips so I want to keep that from happening. Not sure which way to go yet

[gxr02190]

I would probably go with the 265-50-15's. Ten and a half inches is plenty of tire and you'll reduce the tendency to scrape the sidewalls on the body. What's your rear rim width/offset?

[Oztrailer]

I will be getting the 265/50/15's now. Not sure what the offset is but it looks like 8.5" wide and Steven I have tyres and guards