Relationship Between Tire Stickiness and Spring Stifness

Hello, I did not see a (direct) answer in the course materials, but my questions are:

1. What is the relationship, if any, between how sticky a tire is, e.g., UTQG, and the stiffness of the spring?

2. For example, if I use racing coil overs on my car with 200 treadwear tires vs. racing slicks, what would be the adverse effect (if any)?

The reason I'm asking is because I'm wondering if I need softer springs to match my 200 TW or if I can just leave them as is. I hope this question makes sense--I'm brand new to this.

Richard

One would expect the extra grip to increase the lateral (cornering) forces, which would be expected to increase the body roll and camber gain, and suspension deflection if OEM rubber bushes are still being used.

While it's WAY too involved a subject for me (others are MUCH smarter and can go into greater depth), an increase in spring and/or ARB rate may be expected to keep the tyre tread in the most effective contact witht he track surface - especially as "slicks" often have less sidewall compliance.

Personally, as a beginner, I'd suggest you look at upgrading the ARBs as an initial step, as it's relatively cheap, and adjusting the camber to get a good tyre wear/grip balance.

With better gripping tyres, you may also see a benefit in increasing front brake effectiveness.

If you really want to understand the spring balance, you should measure the spring rate of the tire at different pressures. The chassis springs operate in series with the tire spring rate. And the tire tires spring rate always goes up with pressure. This is why you can use guides like "to reduce understeer, lower the front tire pressures, or raise the rear pressures".

I always wondered how they new what side of the ideal pressure for maximum grip you were on. If fact, the spring rate of the tire (and thus the balance of the car) is more important than ultimate grip due to using the ideal pressure. But if you can hit the ideal pressure, what chassis spring rate does it take to provide the ideal balance.

I have built a rig to test tire spring rate with a hydraulic press and a scale pad, I need to update it so I can use different camber angles as well.

So to answer your question -- If the spring rate of the tires in series with the chassis spring is balanced front to rear, there is no need to change the springs. Most likely there is no reason to change your springs with the tires.