Tire spreadsheets

[slngsht]

Michael D sent me this. http://www.usa7s.com/aspnetforum/images/emoticons/hurray.gif

 

 

 

>R Compound DOT Tires

 

 

 

>Slicks

 

 

 

Another one for slicks to follow...

 

 

 

http://www.usa7s.com/aspnetforum/images/emoticons/cheers2.gifslngsht2007-01-21 19:54:27

[roll a 7]

That site does not include Avon, which designs tires specifically for 7s. Their tires are relevant because almost all of the others are designed with 3000 pound cars in mind.

 

 

 

A 7 weighing 12-1300 pounds needs different tire characteristics designed into it. Sidewall stiffness makes a difference. This is also the most likely reason that we inflate our tires to 16-18 psi rather than the manufacturer recommended 32-36 psi. I inflated some Kumho V 700s to 35 psi once and they were terrifyingly bad. Dropped 'em down to 18 and they worked a treat. The National Champ Corvette driver that was using a higher inflation figure was not germane to the optimum performance of my 7, as I learned after copying what he was doing. Over inflation reduces the contact patch on a 7 from a racing slick width to a bicycle tire width----ok, I am exaggerating again but the point is hopefully made: Inflating our tires like our cars weigh 3000 pounds is not beneficial to the handling.

 

 

 

Roger Kraus can be found online and offers various Avons including those designed for 7s. Stokes Performance Tire in Santa Monica, CA also stocks Avons for 7s.roll a 72007-01-20 21:28:26

[slngsht]

That site does not include Avon, which designs tires specifically for 7s.

 

 

 

It's not another site. Michael D started the spreadsheet as a repository for us. He'll be adding to it.

[R1 Seven]

Thanks for posting the list! Another that might need to be added is Hankook.

 

 

 

http://www.hankooktireusa.com/product/tire_race_list.asp?id=racing&t_img=race2&sub_t=dot%20r%20compound

 

 

 

 

[slomove]

Another interesting data collection would be for road tires. For that purpose I am not looking for ultimate dry grip and super light weight (got 13" ACB10 for the track) but reasonable performance and price, acceptable wet behavior and at least 10-15k miles durability.

 

 

 

I was shopping lately to replace my balding Bridgestone S03. But the general trend to bigger wheels has shrunk the selection of performance tires for 15" rims from many suppliers. For my preferred road combination of 195/50-15 and 225/50-15 about the only ones I still found was the Yoko ES100 and Goodrich G-Force. Fortunately at $55 and $90 the Yokos are quite inexpensive.

 

 

 

Gertslomove2007-01-21 10:44:06

[soareyes]

 

I was shopping lately to replace my balding Bridgestone S03. But the general trend to bigger wheels has shrunk the selection of performance tires for 15" rims from many suppliers. For my preferred road combination of 195/50-15 and 225/50-15 about the only ones I still found was the Yoko ES100 and Goodrich G-Force. Fortunately at $55 and $90 the Yokos are quite inexpensive.

 

 

 

Gert

 

 

 

Gert, I've got Toyo T1R's in the size you mentioned above front and back, and as I remember they were 4 or 5 pounds lighter than the Bridgestone's per tire. However, I don't know how they compare to the Yoko's in price and weight, but might be worth looking into:

 

>http://www.toyo.com/docs/tires/tires.asp?lpid=18966&name=Proxes%20T1R%99&category=sport

[slngsht]

Updated the original post with Slicks

[slngsht]

This was provided by Michael D as well

 

 

 

 

Good talking with you this afternoon about tire fitment for your Caterham 7.

 

Here are a few thoughts we talked about pre-Solo event and post-Solo event.

 

First, the DOT A6 competition tire is designed for heavier type vehicles

 

ranging from 1700 - 3000 pounds. Vehicles under this weight should benefit

 

more from using our bias ply slicks which you currently use our item

 

43182R25A - 20.0 x 9.0 -13.

 

 

 

Now, the new Topeka surface was quite confusing, where throughout the year

 

at other autocross events, the bias ply slicks should have an advantage with

 

more initial grip than the A6 which needs some force/weight to generate

 

heat. The Topeka surface proved differently with many people running faster

 

times on the DOT A6 tire. The specific surface(lots of sand) and cooler

 

temps allowed this to happen. I believe it will take several years of Solo

 

Nats to rough up or break in the surface to allow the bias ply slicks to

 

grip better than the DOT A6's.

 

 

 

On to your setup, if you find the 20x9-13 on a 10.0" wide rim is not

 

providing sufficient grip, you should look at running a narrower rim and

 

tire, using a 7.0 - 8.0" wide rim and using our item 43161R25A - 20.0 x 7.5

 

- 13 R25A on the front only with your 20 x 9 - 13 on the rear or the 20 x

 

7.5- 13 on all four corners. The narrower tire should develop heat quicker,

 

but tire wear will increase somewhat, depending on driving style and surface

 

type. This narrower tire combination could offer a second option to

 

slick/sandy surfaces and cooler air temperatures while the wider tire option

 

could be used for hot summer days. Having two tire size options may not be

 

feasible for some because of transportation(carrying 8 rims and tires) or

 

cost.

 

 

 

The other option would be to run the item 46307A6 - P225/45ZR-13 A6 on the

 

less than 1700 pound vehicle using the 9.0" - 10.0" wide rim which seemed to

 

work for a few Solo prepared and modified competitors at Topeka.

 

 

 

Finally, all of this information is a theory or my best suggestion working

 

with tires for 15 years here at Hoosier Tire. I always stress that changes

 

to your wheel/tire combination needs to be track tested before heading to

 

the Solo Nats. Feel free to pass some of these thoughts on to your Caterham

 

7 group.

 

 

 

Jeff Speer, HRT

 

P - 574-784-3152

 

 

 

[trooper8]

My Ultralite is running 17 x 7 wheels. The car weighs in at 1450 pounds without driver. Probably 1675 pounds with driver. I would like to run wider tires (running 235/45/17 DOT's) in the back (the car would make a good drifter since the rear end spends a lot of time about 30 degrees sideways--but sooo good at responding to the throttle). Several people have brought up the point that our very lite cars may not be able to generate enough stick because of the lite weight. I also appreciate someone pointing out that most tires don't have the right construction for the lite cars. What widths are people running on their cars and tire presure (another good point that is opposite the thinking of the fat cars.)   

[trooper8]

good informative spreadsheet. Could it be expanded with some info for us poor folks that are running 17"s

[Al N.]

Trooper, there was a thread on tire pressures not that long ago...I think many of the owners run 18-25 psi. I felt like a complete idiot, because I followed the pressure printed on the sidewall (and not, admittedly, the pressure listed in the Caterham owner's manual).