Benefits of wider tyres vs lighter unsprung weight

[siege]

Wondering about everyone's thoughts about going for more traction with wider stickier tyres vs prioritising low unsprung weight by sticking with stock width wheels/tyres.

I'm the proud new owner of a 2000 nb8a with stock 6kg 15" wheels and el cheapie 205/50R15 tyres (now at 30psi). 5 speed with 4.3 T2 rear end. It's to be a DD to accommodate a spirited driving style.

They seem to let go pretty easily in first or reverse and in second when cornering hard.

So I've got to reading about different options.
1. 15x8 949 6ULs will be the same weight but accommodate a 225/45R15 tyre with almost no increase in diameter (I don't want to lose wheel torque). The options in this tyre size seem quite limited but hankook rs3 seems to be well liked in other threads. Is the rs4 an unknown at this stage?

2. Get 6ULs but stick with a 6 inch wide wheel and put stock size Bridgestone Re003 tyres on. This would be a significantly lighter combination. As a secondary consideration I think there is less poke on this size and so won't fill the guards quite as well.

So what do you think? Is there going to be better grip that will outweigh the heavier wheels to improve handling overall? Anyone running these combinations? I'll get a proper alignment once the new wheels are on of course.

[Okibi]

In out club motorsport (mostly autokhana style), I prefer the 215s over the 205s or 225s. Only based on feel rather than back to back testing. Mine is an SE with a driver who ate too many pies and about 170 at the wheels.

[Magpie]

Unless you are grip limited then wider tyres are not a real benefit. Not to mention they will add unstrung weight.

A set of 7” 6UL’s with AD08R’s weight 15.5kg same tyres on Advanti 8” is 15.6kg.

Get the wheel alignment done first so you can start from a decent baseline. What condition are the other parts of the suspension in?

If looking for decent tyres you can not go past AD08R’s.

[rascal]

If its for a DD, which you stated it was, then stick with the lighter wheels.
Your lack of grip is due to the tyres themselves rather than the size of rim/tyre.

once moving to decent tyres, then the additional grip from then moving to wider rims/tyres is really only found/useable on the track, at the expense of other things, like steering weight, noise, fitment, etc.

[greenMachine]

DD?! No track usage? If the stopwatch is not involved, then is a case of whatever floats your boat, it is all about what makes you happy. On the other hand, if the car is tracked, all that matters is what makes it faster against the stopwatch.

Unsprung weight is an important element, and it comprises wheels, tyres, suspension and brakes. What hasn't been mentioned here is the big savings that can be made with light weight brakes - aluminium calipers, two piece disks with aluminium hats. However, if you are subject to rego inspections, you may not be able to exploit this, or may be limited in how far you can go down this path. Insurance coverage is another question you need to think about if considering this option.

To illustrate this, I have just sold some AP four pot calipers with 280mm x 25mm disks on aluminium hats - they are BLOODY heavy, and would have a detrimental effect on ride and handling, certainly compared to my Wilwood setup. But, they are race brakes, and they have massive thermal capacity to stop a fast car quickly, and repeatedly. If you NEED the braking performance, the lap time, the track position, you will sacrifice other things for that - you will sacrifice EVERYTHING else for that!

In short, for road use you are better off going for the lightest wheel you can find, and afford, and the stickiest rubber. That does not mean a semi slick that needs to be warmed up to perform, but a tyre that grips well from the get-go. It will wear quickly, but that is the price for all that grip.

After that, look at lighter brakes, to the extent that it is feasible/legal/insurable.

However, the above is just theory, and presumes you really need to go that far. You have just bought an NB8A with stock wheels - these are relatively light, and putting a good 195 tyre on them will give you excellent ride/handling/roadholding results quite cheaply. If that is what you are after, stick with that formula. Add some good (not cheapies) coil overs and you will find another quantum jump in handling/ride quality/road holding. On a cost/effectiveness ratio, these will be the biggest bang-for-the-buck things you can do to improve the enjoyment you get out of your car. Invest in quality, not quantity (aka do it once, do it right).

My 2c.

[Lokiel]

Your best bang-for-buck is to stick with the OEM rims and spend the money on decent tyres.

It's amazing the different in grip good tyres can make. My SP23 came with brand new no-name brand tyres and the grip was terrible, actually scary in the wet (on wet roads I couldn't even accelerate hard because the tyres would just spin). Upgrading from the 17" OEM rims and no-name tyres to Mazda CX3 16" rims on Goodyear tyres made the car infinitely safer to drive in the wet.

If you're planning on turbocharging down the track (when you need more rear traction), 15x8s are a good street+occasional track size, otherwise keep unsprung low and use the narrowest/lightest rims available.

[siege]

Very interesting, and food for thought. I think I'm swinging back towards the narrower option. Saves weight and money which can eventually go toward coilovers.

My original shocks still feel strong when I bounce on them though. As the car has only done 53,000km. And I don't feel like it needs to be any lower