Contour Enthusiasts Group Archives Forums Modifications Wheels & Tires hmmm..

18's might give you better performance on a newly paved race track, but there are bumps on city streets... even on most skidpads. If you don't have any sidewall (18's and up) and have stiff suspension, then the tire might bounce off the pavement (while turning fast), instead of absorbing the bump. For that reason, I've seen many autocrossers who drive on the street with their factory 17's, but swap on 16's when they autocross.

How much would a 25" tall tire alter the final drive ratio vs a 24.4" tire? Guess if you have a 3.0 or turbo, you could go the route of tall tires instead of the 2.0 final gear.

So if you don't care about performance (cornering and/or drag racing) then I guess the motivation to purchase 18's are cosmetic based.... so do what you want. Just don't tell me I'll cut faster autocross times if I went from 17's to 18's.

I'll again repeat my points:
1. You can't put too much into the tire calculator
2. 18s do handle better (again IMO from personal experience)

I guess you overlooked the part where I said that I was referring to how the car handles - not speed - that's another discussion entirely.

My car was a daily driver that I drove in a spirited fashion - not autoX. Taking turns and offramps with my suspension, the 18s had less body roll and felt more responsive.

In addition, my car was in fact faster with 18s because I went from heavy 17s to lightweight 18s.

IT VERY dependant on sidewall stiffness, generally lower profile tires will have a stiffer side wall, BUT when comparing identically sized tires, the sidewall construction and therefore STIFFNESS will vary from one typre manufacturer to the other so don't think all tires are the same cos they are the same size.

From Tire Rack...Tire Tech Selecting the Right Tires
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=31

What is the right size for my vehicle?
Buying the correct tire size can get complicated, especially if you decide to upgrade from your vehicle's Original Equipment size. The expert sales team at The Tire Rack is always ready to offer performance and fitment advice. Call 888-541-1777.

A tire's first requirement is that it must be able to carry the weight of your vehicle. No matter how good a tire you select, if its capabilities are "overworked" just carrying the load, it will have little reserve capacity to help your vehicle respond to quick emergency. So when you are in the selection process, make certain that your new tire's size is designed to carry the weight of your vehicle! Don't undersize.

The other size consideration is overall tire diameter. Since many of the functions of today's vehicles are highly computerized, maintaining accurate speed data going into the computer assures accurate instructions coming out. And an important part of the speed equation is your tire's overall tire diameter.

For cars and vans, staying within a 3% diameter change is desirable. Pick-ups and sport utility vehicles (SUVs) are usually engineered to handle up to a 15% oversize tire. Most tire dimensions can be calculated. For more information review the Tire Tech article, "Calculating Tire Dimensions." While at first a 3% diameter increase or reduction in tire diameter may sound very limiting, in most cases it allows approximately a 3/4" diameter change.

Additionally to help with the selection of substitute sizes, a system called "Plus Sizing" was developed. We use Plus Sizing to take into account the diameters of the available tires and the wheels, and then helps select the appropriate tire width that ensures adequate load capacity. Maintaining the tire's overall diameter helps maintain accurate speed data going into the computer.

Well I had to test fit my rims juuust to see what I was up against..I was wrong when i freaked out..The wheels look sick on my car and the whole 225/45 package is amazing!! when i lowered my car off the jack, the car wasnt settled properly yet so you may seem some gaps but man! SOO SICK!!






My Pilot Sport A/S vs. Pilot Sport (reg. summer)

What tiny little brakes you have!

All kidding aside, those look good!

Wow you jacked that car up with the factory jack?!! Yor crazy man, crazy. I hate those little things. If you've ever gotten stuck on the side of the road changing a tire with one of those you know what I mean. My SHO had the same style and damn no fun.