I have a 99 Protege LX with 185 65R 14 tires. Can I put 185 70R 14's on it without any problems to speedo, odo, braking, etc. Same question with 15's: What affect do larger rims have on speedo, odo, braking, etc.? Thanks.

 

i went from the stock rims to a 17 in rim and i have 185 40 17 right now and nothing affected my spedo or anything else but i dont know about going with the 70 series tire

 

Going from a 65 series tire to a 70 series tire means you are going to use a 1/2 inch narrower tire. This may give you equal performance in sand and snow, but will diminish your cornering and braking performance on dry and wet surfaces. 14 is the rim size. If you want to change to a 15 inch rim, you will have to find a tire height that will not change the overall diameter of the wheel/tire package from that of factory wheel/tire package.

Anytime you plus size up your wheel/tire package, you will effect your speedo reading. Plus sizing up 1 inch in rim diameter without the proper tire adjustment will mean that at a reading of 60 mph you will actually be travelling about 66 mph.

Going up in wheel size will also negatively effect your acceleration and braking performance because you are adding "unsprung weight" to the vehicle. This is weight that is outside the suspension that takes more energy to get moving and to stop. Remember, steel weighs more than rubber. The way to offset this to some degree is to go with a lighter, aluminum, magnesium, or titanium wheel package ($$$$$$).

Changing to a non-factory wheel option will also negatively effect the resale value of your vehicle, unless you plan on keeping the original wheels in your garage.

The reason why the tire shop will tell you to upsize the wheel/tire package is simple. Profit. They make alot more money on 15 inch tire than they do a 14 inch. They make a ton of cash selling you new rims. Then they offer to dispose of the old rims for free. Then they take the steel rims to the scrap yard and get $5 a piece for them. And you didn't even get kissed first!!!!

My recomendation is always to by a good quality sport tire that is the same size as the factory size.A fewgood tires for your Mazda is the Dunlop SF series, the Yokohama AVID, and the Michelin Destiny. These will give a sport performance ride(smooth, but you will still get a good road feel) and will give you long life. Also, a good quality tire will give good peformance throughout the life of the tire.

Stay away from Goodyear, Firestone, Mastercraft, Toyo, Kellyand any other off brand tire. You may save a few bucks now, but you'll be back buying tires in no time.