For the last few years, I have been all about learning how to lower my car properly. Well, the more I learn the more I have come to believe that it isn’t right for me, at least not where I drive: NYC. Instead, I’m going in the opposite direction: I am going to raise the height of the vehicle by a little bit (.75 inches)
My car comes OEM with 185/65R15 tires on a 15x6 (typical econocar)
I went with a set of aftermarket wheels (lightweight) 15x7 with 195/60R15, I find the handling improved in some scenarios such as curves but the car also suffers more bump steer and torque-steer (haha! I Know! torque!? on a weak cheap econocar?) and the ride is not as comfortable as I would like.
I have decided to go with a set of Michelin Defenders in the 205/65R15 size, this raises the car about .75 inches (rolling diameter of 25.5 inches vs. 24.2 inches on the 195/60R15 tires.)
THe benefits are:
1.) I don’t need to be as careful around the terrible roads in NYC
2.) the greater rolling diameter MIGHT mean better gas mileage as the gear ratio is taller. As it is now, I don’t get very good gas mileage, even on the highway
3.) The new tires are ‘Low rolling resistance’ ---- I like that!
Thank you for listening. Please feel free to critique my reasoning process.
Are you prepared to compensate for the difference this will make in your reported speed? Larger diameter tires will cause your speedometer to report that you are going slower than you are actually going.
Wider tires look cool, but they generally offer more wind resistance than narrow tires.
A measly .75 increase in height is not worth the money in my opinion. Rutted roads and streets demand careful driving and 0.75 inches will not save your undercarriage if you are careless.
I would just leave things alone. As others point out it will throw off the speedometer and might land you a ticket in a radar speed trap.
You might get a small increase in gas mileage; you will get a better increase in mileage by fine tuning your driving habits.
In order to know if you’re really changing gas mileage, speedo accuracy, and/or odometer accuracy, you’ll need to do some calculations. www.tirerack.com has a calculator that should help.
That bump steer and torque steer may have come from a change in offset between the old wheels and the new wheels. A heavier combination, causing the axles to have less advantage over induced steering forces due to the larger diameter and greater weight, could have contributed to the torque steer and the bump steer. Offset, diameter, and weight really do matter in much more than speedo/odo accuracy.
Clearance from tire to fender lip or strut is crucial. I can put my hand on top of tire and feel the strut coil with the back of my fingers. That means it is about 5/8" from tire to metal! Don’t go crazy on your BIG tire plan.
I think the big tire plan will get you onto trouble. The original tire size, 185/65-15 had a 120.25 mm sidewall height. The current tires, 195/60-15 have a 117 mm height. The proposed tires, 205/65-15 have a 133mm sidewall height. That’s 26mm taller overall tire than stock, a complete inch. That may be enough to start rubbing on things metal and maybe sharp.
This also doesn’t take offset differences into account, as @Cavell and TSM mention. I’d recommend getting 205/60-15 tires, since the sidewall height is 123 mm, and overall tire height of 5.5mm taller than stock. Much less chance of fitment issues.
A tire with a 3/4" larger diameter will raise the car only 3/8", the distance from the wheel center to the road ( the radius ).or 1/2 haqlf the diameter.
To add to busted’s comments, remember to consider the wheel offset too. Stick 'em out more and they may look purty, but also induce handling weirdness.
Wider tires look cool, but they generally offer more wind resistance than narrow tires.
I think that Manolito meant to say that wider tires are likely to have more rolling resistance than narrow tires.
One tire study about tire width, quoted in a Consumer Reports discussion forum, was done by the German ADAC automobile club and the Austrian Automobile Club. They found that lower sidewall wider tires had more rolling resistance due to increased wind resistance.