Increase track=lower lap times????, is wider better?? Options

[Mueller]

I thought I read someplace where someone was claiming that by increasing the track via wider wheels and tires a few inches(or even spacers) it was equivialant to a 100hp increase in power on large track

I know that is just way too much of a general statement, but could it be based on facts??

[Blake]

Widening the track can be benefitial to lap times, but there is more than one way to do it. One way is to increase the offset of the wheels, which is by far the most common approach. This is what you are doing when slapping wide rims under a body kit. It can also be done with spacers and stock rims. In either case, you are messing around with the suspension geometry and will usually be making some sort of tradeoff. Bearings will wear faster. The scrub radius is increased, making steering harder, tires wear more, and it will cause more "feedback" from surface irregularities (not always good, btw). I believe it would also change the wheel rate. Basically, it is a hack. Race cars often do it because they are typically restricted by regulations from doing it right and they are more than willing to live with the tradeoffs. The "proper" way is to literally move the suspension outward and/or change the geometries (like kingpin inclination). This is how it would be done by the factory or by well-funded race teams in advanced series. Not exactly grassroots DIY stuff.

I see no problem widening the track of a car moderately, as long as the benefits outweigh the tradeoffs. Like lowering the car, less is often more. Be conservative as you can afford to be.

BTW, the reason a wider track is "better" (in some respects) is because it reduces weight transfer. Weight transfer is "bad" (in some respects) because while the grip of the loaded tire increases, it does not increase at a greater rate than that lost by the unloaded tire (presuming good camber control, etc). Other ways to reduce weight transfer include lowering the Center of Gravity (CG) or reducing the weight of the vehicle. Increasing the wheel rates and/or roll stiffness can also help in a practical sense. So, there are alternatives that are equally effective and often less costly in terms of tradeoffs. This is all oversimplified, but true in general presuming I didn't mistype or have a brain fart.