zland

I know many of us are upgrading tires and suspension on our 350Z’s. As of yet, I have not seen much hard data on what tire, suspension, and sway bar packages have on improving lateral grip besides such articles as Sport Compact Car October 2002 that measured stock lateral grip at.88g and then measured .98g’s by modified tires (Toyo proxies F: 235/40ZR17 & R: 255/40ZR17) and suspension: Ft: Ground Control coilovers, Rear: Ground control Advance design shocks.

In the September 2003 article in Car and Driver Magazine, it compares the tire and suspension packages (Base, MSRC, Z51, and Z06) offered on the corvette.
Please do not flame me because I know that you cannot directly transfer one car’s test results to another cars results when modifying tires and suspension but I do think you can see a general trend. The data I am posting below is just “food for thought”. I hope that others can post hard data on how their Z’s lateral g’s improved when upgrading tires/suspension.

Testing lateral grip on Corvettes:

The first variable is tire type and size. Base, MSRC, Z51 suspensions have Goodyear Eagle F1 GS extended Mobility tires (F: 245/45ZR-17 & R: 275/40ZR-18). The Z06 suspension has Goodyear Eagle F1 supercar (F: 265/40ZR-17 & R: 295/35ZR-18).

The 2nd variable is suspension types. The spring rates, roll bars, and shock absorbers all vary slightly with base being the softest and the Z06 being the stiffest.

The testing measured lateral G’s with Stock tire sizes and stock suspensions and then all were measure again using the Z06 tires (F: 265/40ZR-17 & R: 295/35ZR-18). These tests isolated the impact that tire size/type and suspension modifications have on lateral grip.

Results with stock tires:

Base suspension = .91g
MSRC suspension = .91g
Z51 suspension = .92g
Z06 suspension = .98g

Results when Base, MSRC, Z51 suspensions used Z06 tires:

Base suspension = .93g
MSRC suspension = .96g
Z51 suspension = .96g
Z06 suspension = .98g





Summary: Applying the tire and suspension data on the corvettes to the 350Z.
Tire type and size had a big difference in lateral grip on the corvette. On average, the corvettes with Base, MSRC, and Z51 suspensions improved their lateral grip by .04 (varied from .02g’s to .05g’s improvement) when improved tires were added.

Based on this data, I am assuming that our Z’s can have improvements with tire upgrades. IF the same improvements resulted, this would bring Z’s from stock .88g (Road & Track Aug. 2003 test specs) to approximately .92g by adding .04g’s improvement.

In addition, even with all Corvettes using the same Z06 tires, the Z06 still had between .05g (base suspension) to .02g (Z51 suspension) more lateral grip thus suspension and sway bars increased lateral g’s as well. Again, this is assuming a NISMO S suspension and sway bar package or coilover’s could possibly improve the Z’s lateral grip like the corvettes did. If upgrade tires on the Z did give us about .92g’s and lets say an upgraded suspension could gain between .02g - .05g’s, this would make the Z’s lateral grip somewhere between .94g to .97g’s. This seems likely since the Sport Compact Car October 2002 article measured .98g’s on the 350Z with tire and suspension upgrades.

I hope this data helps and I would appreciate someone’s experience or information they might have on this issue. If you know more than me, correct me but please do not flame me….Jeff

ares

iTrader: (2)

that test is wierd actually.

as the Z06 did not matter which tires it had, it got .98 with base tires or its own stockers. so tires didnt help it at all, they extra performance tread they gave it was worthless.

I dont think thats true... but I do think that test seems to be flawed somwhere...

Redline350Z

The Z06 used the better tires for both measurements - they ARE the stock tire on the Z06. The other three cars changed from the base tire to the Z06 tire.

zland

Redline 350Z is correct. They put the Z06 stock tires on the other Corvettes so that they all had the same tires thus they could accurately compare the lateral G's of all suspensions (remember, to accurately measure, you must have only one varible). If the tires on each model are different, you are not sure how much the tires or suspension have an effect on lateral G's.

Jeff

rodH

iTrader: (2)

Jeff your mailbox is full

zland

I erased a bunch of files so PM me again Rod.....

D'oh

Keep in mind that all of the models except the Z06 use run-flat tires. Obviously they do not perform nearly as well as "normal" high performance tires.

Also, on the SCC test, they changed to Toyo Proxes RA-1. These are race tires, which will have a huge improvement over street tires in terms of grip.

Unfortunately, SCC didn't test the new shocks with the stock tires, so it's tough to know how much of the lateral G difference was due to tire and how much was due to suspension.

Maybe the difference between Run-Flats and normal tires is similar to the difference between normals and race, and therefore the Vette example is a good indication of how much of the difference was due to suspension VS tire.

I think for the Z we really need to increase the neg camber in the front (in order to improve balance) and then add big f-ing tires like on the Vette. Since we weigh about the same, we'd need about the same amount of tire to keep up (assuming it was all contacting the road).

Either way, it's a bit humbling to know that the stock Z with race tires is still not as grippy as the vette on street tires. It'd be interesting to see what a "designed" suspension could do for the Z (or maybe just some adjustable arms for the front).

-D'oh!