New Tires

I need some new tires for my 96 h/b. I figured I'd give the Kumho 795's a shot:

http://www.tirerack.com/tires/Compare1.jsp?width=155%2F&ratio=0&diameter=13&startIndex=0&search=true&pagelen=20&pagenum=1&pagemark=1&x=76&y=13&RunFlat=All

I've driven my current tires through some pretty bad weather and I drive pretty careful. These seem to have good reviews on epinions:

http://www.epinions.com/auto-Tires-All-Kumho_795_Touring_A_S_175_70_SR13/display_~reviews (http://www.epinions.com/auto-Tires-All-Kumho_795_Touring_A_S_175_70_SR13/display_%7Ereviews)

Has anyone here had any bad experience with them as far as performance?

Also, are 155/80/13's the best size?

Thanks

I bought these about one year ago also from Tire rack. Deliveed to my front door by UPS. I then took them to my local Walmart for fitting. So far no complaints. I did consider bigger tires (larger diameter) but was unsure how they would perform so decided to stick to the 155s. There was feedback from someone at that time (on this forum in fact) that larger tires would result in a smoother ride - cannot comment on whether this is true or not. Also if you use larger tires your speedo will not be as accurate.

I also believe that you can plus size them for better handling but I do not know how much extra power is needed from the engine for that. Also you will need larger wheels which is an added expense.

Thanks SD,

I tried to do a search on this topic and got confused by all the different sizes people use. I used to have a 94 Metro with the 12 inch tires and I like the increase to 13 inches with the 96. I'm not sure I notice too much of a difference though although I suppose I'd notice more in a side by side comparison. I feel a little better on the rougher roads with the 13's though.

With the 1.0 L, 5 sp the last thing I need is to need more power to turn the wheels. Without doing anything radical, I would guess the easiest improvement would be to get the narrower tires instead of say 70's so the tire has less surface area to ride on top of slush etc.

Thanks for your feedback.

Did not understand the "70" in your post - are you referring to the aspect ratio. If you want narrow tires you need to find something less than 155 - however, I have a feeling that 155 is the skinniest tire on the market. I guess thinner tires will require less power to move the car but the tradeoff would be less grip on the road due to a smaller surface area and hence less friction.

Oops I was thinking of another car when I used the term "70's" but yes I was referring to the aspect ratio.

I do think the 155's are the skinniest and my thinking is that traction would be increased on the smaller surface area due to the pressure on that area.

If the total weight stays the same but the area of tread contact decreases as it would in a skinnier tire, more weight will be exerted by the tread on the road surface which I think would increase the grip the tires have.

And of course the opposite would be if you were to drive on sand, you would want a wide tire which would be less apt to sink in due to the increased surface area and decreased pressure exerted on the contact area.
Of course I've been known to be wrong. :screwy:

Suffice it to say, I've ordered the 155's :)

LOL....it has been many years since I studied applied mathematics and physics but this is as I recall - pressure is force per unit area so if you have a skinnier tire since the weight of the car remains the same the pressure on the contact area will increase due to decreased surface area but the total force will not change. However the decreased surface area will have less grip and thus friction will be reduced making it more likely to slip and slide. However this will also make it easier for the engine to pull the car.

And as I see it a wider or narrower tire will not help the sinking in the sand since total force has not changed even if the surface area has. All the wider area does is to reduce the area over which the total force is applied and that will not change unless you lighten the car.

http://smiles2k.net/smiles/big_smiles/super_smilies088.gif

Touche!

Ok, ok no mas. LOL

Thanks for the correction though.


I await my 155's :smokin:

Sorry - I have to travel to Europe in about an hour so only a moment for a quick reply. Your definition of pressure is incorrect - pressure is defined as force per unit area - ie Force/Area - not the product. The other thing a quick glance at your post I noticed - you say force increases - no it does not - the pressure increases. The force is the mass of a body X g and in this case that would be approximately 1/4 of the wight of the car assuming the weight is distributed evenly.

A link on Wikipwdia on the definition of pressure - http://en.wikipedia.org/wiki/Pressure

I will have a better look at your post when i get back.

Hi SD,

I edited the post LOL

But I'm absolutely positively certain that the width of a tire influences traction.

Have a good, safe trip friend. http://users.pandora.be/eforum/emoticons4u/happy/045.gif

Sticking with the skinny tires is the right choice, man. Wider tires are good for dry-weather traction, put them on a musclecar. I'm guessing you don't usually overpower your tires in your 1.0. I sure don't! My biggest fear is a spin-out when I hit a big puddle or some slush on the expressway. You want those itty-bitty skinny pizza-cutter tires to get thru that stuff. The skinnier they are, the less likely to hydro-plane.

Hi Rdon & SD,

Agreed my friends.

I really screwed up trying to say anything mathematically http://www.userbars.net/forum/images/smiles/ashamed.gif so I guess I'll try a verbal analogy:

Running wide tires through water/snow/slush etc is like trying to cut a steak with the knife sideways. It doesn't matter how sharp it is, it won't cut through. :naughty:

Thanks!