I have a Nissan March whose tyre size is 165/70 14, a rare size to find locally. I have been told to change to 175/70 14 but I am reluctant to do so. What's your advice? Ndung'u wa Munywe
The two fundamentals of any such change are the size of the wheel rim and the space inside the wheel arch. The 175/70 tyre will be wider and have slightly taller walls.
The original wheel ideal for a 165/70 tyre will be a 14-inch 5.5J. It will only fit 14-inch tyres, but will probably give a snug and safe enough fit to a 14-inch tyre that is one size wider or narrower than the 165. Not more than that. Double-check with a specialist and take a common-sense look at the result when a wider tyre is fitted.
I am surprised that 165/70 tyres are hard to find. They are a “common” international specification. If the minor change-up size is more readily available, the difference in most respects will be marginal, and there will probably be enough wheel arch space to avoid “scraping” when the suspension is squashed or the steering is turned to full lock.
Still to a minor degree, the tyre will be slightly heavier (with a fractionally negative effect on performance/economy) and have a slightly larger circumference (marginally altering your gear ratios, increasing your potential top speed, reducing your acceleration, and by the same degree falsifying your speedometer and odometer readings). All by just a few percentage points.
