tire opinions

For road racing, autocrossing, or just taking that curve in style. Oh yea, and stopping!
buggpower
Posts: 160
Joined: Fri Aug 11, 2006 1:32 pm

tire opinions

Post by buggpower »

I bought a set of rims and am undecided on the tire sizes.They are 13x5.5 and 14x7's. The 13's have a perfect offset and fit nicely inside the wheel wells so I dont think narrowing is required.So I was thinking of a 165/65 175/60 or something similar but without the balloon effect.There about 21-22" tall and similar to a 145/65/15.With those I would lower it only enough to where I have about and inch gap from the fender and tire.The 14's I would run a 195/60 or similar.Do you guys have better options for me?If so could you help me decide.
I also looked at a 155/80/13 but I dont want a front tire with a taller sidewall than whatever I decide for the rear.
Thanks guys
User avatar
FJCamper
Moderator
Posts: 2910
Joined: Wed Nov 14, 2007 2:19 pm

Be careful

Post by FJCamper »

Hi Bugpower,

Be careful here. Tires are not chosen entirely for their cosmetics.

Use a common brand, so the general handling is close to the same front and rear.

Low-nose Bugs can handle funny, one of the main reasons Porsche kept their wheel diameters the same front and rear, but made the rear wider for a tire with more grip. The front and rear ride height was also the same.

I'm not just advising from a "purist racer" viewpoint where I think you ought to be setup for the track, but different diameter wheels, different sidewall profiles, and a low nose and high tail makes for spins in the wet most of the time and in the dry some of the time just braking, let alone turning.

Good luck -- FJC
User avatar
Marc
Moderator
Posts: 23741
Joined: Thu May 23, 2002 12:01 am

Post by Marc »

Have you considered the effect such small-diameter tires will have on your engine speed on the highway? 195/60-14 rears would lower your effective final drive ratio by ~10% - instead of ~3500RPM @70MPH your engine will need to buzz at ~3850.
165/65-13 fronts will throw your speedometer off by ~15%...when it says 70 your actual speed will be closer to 60.

Assuming no suspension ride height changes, simply bolting on front tires that are 1-3/4" shorter than the rears will cause you to lose around 1-1/3° of caster which will adversely affect straight-line stability on the highway, too...you should expect to fit some shims between the lower beam tube and the frame head to tilt the beam back into its original relationship with the ground.
buggpower
Posts: 160
Joined: Fri Aug 11, 2006 1:32 pm

Post by buggpower »

Marc wrote: Assuming no suspension ride height changes, simply bolting on front tires that are 1-3/4" shorter than the rears will cause you to lose around 1-1/3° of caster which will adversely affect straight-line stability on the highway, too...you should expect to fit some shims between the lower beam tube and the frame head to tilt the beam back into its original relationship with the ground.
What do you mean about losing stability in straight lines? Anyways this isnt a race car , to clear that part up.Also I am aware of the speedometer changing and the revs changing.I figured it shouldnt be much.The fronts, what would you guys run on the 13" rim? I would run a taller tire but I figured it would look funny if I got tires up front that have a taller sidewall than the rears.
I have seen guys run the 195/50/15's up front an there around 22". How much of a drop would I need to lower it to get a small gap.
The bug has 195/60/15's on it right now, they are 24" tall.I figured if I get something in a 24" area it would be ok, since the stock ones are what, 25"?

Heres my wheels by the way.
Image

Image
buggpower
Posts: 160
Joined: Fri Aug 11, 2006 1:32 pm

Post by buggpower »

Anyone on here by chance know any places that sell a 175/60/13 that isnt for competition use?I checked Tire rack and couple others but just comp tires.
Also would you guys think a tire with 200 AA tread would be ok for a daily driver (rear tires 195/60/14)
User avatar
Marc
Moderator
Posts: 23741
Joined: Thu May 23, 2002 12:01 am

Post by Marc »

Try Falken.
http://www.discounttire.com/dtcs/search ... d=13&ar=60
The ZE-512 is discontinued (superceded by the ZE-912) so you might be able to find a closeout price on them if you shop around.

200 is a pretty low wear index number these days, sounds like those are some fairly racy tires. They'll work fine, just won't last too long.

175/60-13s are only 21¼" tall, that'll cause a huge (~17½%) speedo/odo error compared to the stock 25.8" 165-15.

195/60-14s are 23¼" tall, so your gearing will be ~10% shorter than stock (3300 vs 3000 RPM @60MPH).

Caster is what keeps your wheels wanting to roll straight ahead rather than flop from side to side. If the chassis is lower in front the beam gets tilted forward at the top, and may need to be shimmed out at the bottom to compensate if you find that the car drifts/wanders on the highway.
Post Reply