14 vs. 15 inch tires/wheels

#1

Ok, so as I am trying to wrap up my build, the costs are rapidly escalating - wtih all of the safety gear and other items on the short term horizon, I am thinking that in order to save some $$ I might go with 14 inch tires to start out as I have several sets of wheels available, while my only 15 inch wheels have a good set of Hankook Z214s I’d just as soon leave on there for CCA days or other open track/non-Spec use.

Given that I will be just starting out as a Rookie, and do not expect to be much mroe than a back marker for a while, am I really hurting myself performance or development wise by going with the 14s?

It seems they are essentially the same rolling diameter - just a narrower wheel and a little more sideall to flex, I guess.

Anyone care to share their insight?

#2

I think it made a much bigger advantage with the RA-1’s and there super soft sidewalls. With the R888 I think that the 14 really doesn’t have any disadvantages, but might possibly have some advantages…What does everyone else think?

#3

R888’s have different sidewalls? How might that affect handling?

#4

Consensus is that the r888 has stiffer sidewalls and is around 5mm wider.

The tire is part of the suspension. So the profile, overall sidewall stiffness, and pressure all influence how the tire responds when load is placed on it.

The less deflection from the tire overall should equate to a more consistent feeling tire, better turn-in, etc.

I’ve heard it described as a spring and I think you can calculate its stiffness similar to a spring. Or I could be imagining that. Math isn’t my game.

I don’t think the r888 is available yet in 14in so that may help make your decision.

#5

Okay, this is definitely overkill but there’s an interesting “how tires work” thread on the Clemson Sports Car Club boards:

http://clemsonscc.com/Forum/viewtopic.php?t=8296

#6

IndyJim wrote:

[quote]

I don’t think the r888 is available yet in 14in so that may help make your decision.[/quote]

The 14" is available as I have finally seen them with my own two eyes. I will probably pick up a set for spares…They are only a dollar less a tire…

#7

Usually the biggest difference between the 14 and 15 inchers isn’t the tire difference but the weight of the stock wheels vs. aftermarket 15’s.

For you rookie year it’ll make no difference once so ever. I’d just make sure to have 2 to 3 sets of whatever size wheel you choose to make rotating through the tire life easier.

JP

#8

Yeah - the tires are essentially the same cost, but I have plenty of 14" wheels to use, but just the one set of 15s.

Looking to save $$ by not buying more 15s just yet.

#9

Fred42 wrote:

[quote]Okay, this is definitely overkill but there’s an interesting “how tires work” thread on the Clemson Sports Car Club boards:

http://clemsonscc.com/Forum/viewtopic.php?t=8296[/quote]

Great thread Fred.

#10

Run 14" on shorter tracks… Run 15" on longer tracks. Helps with the gearing… but to be honest, I’d run 225/14s…

#11

You have two tire size choices per the rules: 205/55/14 or 205/50/15. From my back-of-the-napkin math, the difference between the two diameters is about 0.2" (about the same as the difference between a 6/32nds and 3/32nds shave).

Not that it matters if you’re just starting out, but some folks like to be fully legal from the get-go.

Steve D.

#12

Well I just looked the rule book and Steve you are right… I wasn’t aware after June 2nd, 205 must be used…