Has anyone used R-compound tires in 175/50-13?

Ulix

Ulix

True Classic
Hi all,

I just did a hillclimb this weekend ([ame="http://www.youtube.com/watch?v=Al820NG8T4Q"]YouTube- Ransel Classics 2010 - 1974 Fiat X1/9 - 3:11:22[/ame]) and my Hankook Z211 tires (185/60-13) had very nice grip. :)

But I notice that ever since I swapped the final drive in my 4-speed from 4.08 to 3.67, my gearing doesn't fit so well anymore for track use. The swap changed rpm by 10%, so what used to be 6000rpm is now 5400rpm. Very nice for the interstate (that was the plan), but the original final drive was better for both track and hill.

The Yoko A048 is available in a 175/50-13 which is very short, increasing rpm by 8,3%, almost making up for the final drive change. It would also lower the car some more. This option seems tempting for when my current race tires are worn out. On the street, this would let me keep the reduced rpm with street tires in 185/60.

Has anyone used this race tire in this size? Any drawbacks due to the small diameter?

(Yes I could go to a 5-speed setup, but that is heavier, doesn't shift as nice and my 4-speed is rebuilt)

Thanks, Ulix
 
Nice job!

Looks like a very fast and fun hillclimb.

Did you ever race with either Lil' Mikey or Big Mikey Hokensen (sp?) Anyways, Big Mikey had a 74 with a very hot 1500, dual carbs, blah, blah, and ran on 175/50/13 tires. He was very quick in it.

This size of tire puts your tire diamater at almost 20", which is pretty small. In comparison, the race slicks in 13" sizes are 20x8x13, or 20" tall, 8" wide, and 13" rim.

I have raced these with both the 4.08 gear set and the 4.41 gear set. The 4.41 set with these small tires is fun as you can get from first to third gear in about 2 seconds.

For the race you just did, it would put you in more of the powerband of third gear, vs. the lower end of third.

I would go for it.

BUT... You and I both know about hillclimbs. It is not a matter of if you will crash, but when you will crash. Maybe it's time to build a purpose built race X?

Take care!

Eric Armstrong
 
Just the regular tire in 175/50-13

That looks like the roads I grew up on in eastern Ohio! LOL I miss those days...

I've been running that size tire on the front for years with no issues. I've put them on the back a couple of times just to see what that kind of gear drop feels like, (very snappy) but didn't have them on there long term.

I went the other direction with my X and put 4.54:1 gears in the diff and larger tires on the car (225/50-15) for a wash in gear ratio. Putting the stock size tire (185/60-13) on the car drops the gear ratio down quite a bit. When (and if) I auto X the car, I might go down to the 175/50-13 tires for some crazy hole shots out of the corners!
 
UberKewl Ulix!

Fabulous footage of fabulous X with fabulous driver!

As E-strong noted, the pastel yellow X previously owned
by Lil' Mikey and his dad Bob Hokanson ran 175-50s.
Yoko 008s they were. Had 4.42 gears too!
They weren't R version of the 008, so not overly sticky compound.
Yet, dem boyz was quick in that car.
I suspect primarily due to driving experience,
as a less experienced X driver running same tires
and similar engine/suspension didn't run in same league as the Hokie Boyz.
Later, Hokies ran noticeably quicker on R compound Hoosiers.

Only drawback to short tire is giving up a bit of fore/aft footprint.
Upside is reduced rotational inertia for improved braking/acceleration
and less sidewall flex of course.
To what extent I'll leave to cypherin' types.
All of which I suspect to be relatively minor
compared to the real issue...which is rubber compound.
If the 048 compound is comparable to your Hanooks,
then I say go for 'em.
If 048 compound is harder than Hanooks,
perhaps try'em and see if theoretical upsides
are enough to compensate for harder compound.
 
I ran the Advan A048 in 175/50/13 back in 2005

It stuck very good. I have g-force suspension and many custom hiem joints and stuff under the car. It would stick better then I was capable of driving with 4 years worth of auto-x experiance at that point. I didn't have a g-meter on it but it stuck better then my buddies civic that was seeing over 1.2G consistant lateral and 1.4G transient
 
Can't speak to the tires... but...

Great fun to watch!

Thanks for posting... ya had me leaning a bit at the end!

HA!
 
Hi Eric!

I remeber a certain video you took in your 128. I believe "Well, hell!" were your words as your 128 slid sideway up the hill. :)
Crashing is definitely a concern, but I have no time or garage space for another car. :-(

Now that you mention it, I remember the yellow Hokensen-X with the 7" Compomotives and thoses small tires. Looked awesome! But it is hard to get an X low enough for this tire to look right.
 
Thanks Mike!

Wow, short tires with super short ratio. Must have been a blast. :)

The 048 is available in medium and soft. So you think I should go for the soft compound? Will it last more than 2-3 events?
I have no experience with this.
I know my BFG R1s I had in Seattle lasted forever. :)
Bought used from Mark P., used for a couple of years and sold them to Mark F. (ok, he wanted the rims).
 
Wow, that sounds promising.
I think I'll give it a try if the tires are really still available as they claim. Will be getting them from GB.
 
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