[Rwg]

I just received confirmation on the new sizes that Kumho will be offering the 710 in next year:

225/50-16
215/40-16
245/45-17

They may offer more sizes as well. Do you think the 215/40/16 and the 245/45/17 will fit and work well on the Elise?

I will try to find out when they expect these sizes to arrive in the U.S.

 

[Rwg]

Delivery in 1st Quarter 2005

I just got a response from Kumho that the new 710 sizes will be coming in the 1st quarter of 2005.

I have read that the 710 is much wider than the Ecsta 700 that it is replacing. In fact, according to some people on SCCA forums, the 205/50/15 710 is almost as wide as the 225/50/15 ecsta 700. Also, the 205/50/15 V710's are virtually the same width as the 225/45/15 Hoosier SO3's.

What are the odds that a 215/40/16 and a 245/45/17 v710 will fit an Elise considering they are much wider than their "listed" sizing suggests? If the 205/45/16 Hoosier s04s were tight is there any way that a 215/40/16 Kumho 710 will work?

Randy, what do you think?

 

[Randy Chase]

Kumho news release on their sizes-

http://kumhousa.com/News/News2004.asp#nov1d

Five more sizes in April--215/40R16, 225/50R16, 245/45R16, 245/35R18 and 285/30R18.

NO new 17s????


Existing 17s-

275/40R17
295/40R17
315/35R17
335/35R17

 

[Stan]

I think the 245/45 will be too tall for the car...but it may turn out to be short after all. We need more information! For autocross in stock class 1/4 inch changes in offset are legal which may help out. I wouldn't mind seeing a smaller diameter than stock rear tire size to help out gearing and lower the car a bit.

 

[John Stimson]

Re: Delivery in 1st Quarter 2005

In fact, according to some people on SCCA forums, the 205/50/15 710 is almost as wide as the 225/45/15 ecsta 700.

That's true (corrected the size of the ECSTA, there isn't a 225/50-15).

Also, the 205/50/15 V710's are virtually the same width as the 225/45/15 Hoosier SO3's.

That's not true. The 205/50-15 V710s are significantly narrower than 205/50-15 A3S04s, and according to people who have made direct comparisons the A3S04s are not wider than the A3S03s.

 

[Mean TT]

I wouldn't mind seeing a smaller diameter than stock rear tire size to help out gearing and lower the car a bit.

It almost sounds like you might want more torque, no?

 

[Randy Chase]

It almost sounds like you might want more torque, no?

He may or may not want more torque (and who wouldn't?) but a lower profile tire that improves gearing actually to me has more benefit in keeping the car in the cams on many autocross courses. Of course of faster courses, you might want a taller tire.

However, the larger benefit is lowering the center of gravity of the car at the same time you are reducing rotating mass and tire sidewall flex.

 

[Mean TT]

He may or may not want more torque (and who wouldn't?) but a lower profile tire that improves gearing actually to me has more benefit in keeping the car in the cams on many autocross courses. Of course of faster courses, you might want a taller tire.

However, the larger benefit is lowering the center of gravity of the car at the same time you are reducing rotating mass and tire sidewall flex.

It was in jest. Also, by lowering the back of the car, I think it would effect the balance of the car a little more than an addition of more power, however that was achieved. I was only referring to this as a response to other posts.

 

[Stan]

>>>It almost sounds like you might want more torque, no?<<<

The lowering without changing suspension angles is helpful.

Many local autocrosses top out at about 55-60 MPH. 2nd gear takes us way past that speed. So technically if we could change the gearing it would make sense to do so. So we can spend more time in the engine's sweet spot. In stock class you can't go into the gearbox. But you can get some slight benefit from the gearing change associated with a smaller diameter tire.

It's very common in autocross to use significantly shorter tires. It's rare to use significantly taller tires.