Top Gear Philippines

Hello, Top Gear Philippines! Plano po namin palitan ang original 17-inch rims ng Mitsubishi Montero Sport po namin to 20-inch since three years na rin ito at kailangan na palitan ang tires. Any advice kung tama po ba na mag palit ako to bigger rims? May effect ba sa engine performance ng sasakyan namin?  Saan maganda bumili ng alloy rims? Thank you and more power!

Michael from Isabela

Hello Michael,

When it comes to changing wheel and tire combinations, it's best to know the following formula (who knew in kindergarten that math could be so useful?):

outside diameter = (tire width x aspect ratio)/100) x2)/25.4 + wheel size

This will give you the outside diameter of your tire. Your speedometer will be calibrated to this outside diameter (within a certain percentage). Change the outside diameter of your tire and you change the speedometer reading versus the actual speed of your Mitsubishi Montero Sport.

You can also change your rate of acceleration. Bigger tires equates to slower acceleration and a higher actual vehicle speed versus the indicated speed. The reverse applies, of course, if you go with smaller outside diameter tires. 

Having too big a tire may also cause you clearance issues, particularly when you go with a much wider width tire.

Apart from tires' outside diameter and tire width, you also want to be aware of wheel offset. Too much in either direction and the inner edge of your tires will be hitting the wheel well when you're turning, or the outer edge may scrape against the fender edges when going over road imperfections. Ideally, you'll want a wheel with an offset that will still maintain the same ratio of how the inner and outer half of the tread width is located within your wheel well.

Note that going with a bigger wheel will usually reduce the sidewall height as well as change the ride characteristics of your Montero Sport. It's the possible change in impact harshness that you have to watch out for. However, most motorists are also willing to overlook that aspect for the cosmetic improvement.


Head over to any knowledgeable SUV wheel and tire specialist store that carries the wheel and tire you want.

Thank you for the well wishes and do send us a photo of your ride with its new wheels and tires!


Ferman Lao
Technical Editor
Wearing the hats of a race car driver, driving instructor, grease monkey, tuner, dyno operator, auto shop owner, motoring journalist and CAGI president at one time or another, or all at once, deep down he's just another guy who loves cars.
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