Wider Tires = LESS Traction ??

[Katmandu]

Ok, I just upgraded the rear tires on my mildly modified 91 GT. I went from worn out 245-45-17 Goodyear Eagle ZR Gatorbacks to 275-40-17 Kumho Ecsta Supra 712s.

My car now looses traction MUCH more easily than ever before! Even going from worn out tires to NEW tires! The car is no longer fun to "hammer on" since it breaks traction so easily.

The Kumho's have very good reviews on www.TireRack.com and have an 8.3 Dry Traction rating. The Gatorbacks have a Dry Traction rating of 8.0.

I'm wondering how much the COLD temperatures have to do with the Kumho's compound. I'm thinking since the temps have here (Dayton, Ohio area) have been below 25 degrees (the last few weeks) that the rubber has become HARD and therefore giving LESS traction.

IDEAS ????

 

[ttop88]

Kumho's are a cheap tire. The price reflect in there actions as well. I had 712's and put 40000 miles on them but if it's not 80+degrees outside they are worthless. On top of this, if you put that 275 on a 8"wheel instead of a 9" it will be just as crappy for traction. What wheels are you running?

 

[wythors]

If they are a summer compound then, yes, the temp will have a lot to do with it. My Eagle GS-D3s even came with a warning that driving them in sub-freezing temperatures could be dangerous. That said, I agree that Kumhos are crap and I wouldn't run them if you gave them to me.

 

[blckstng96]

first off they are a cheaper tire,2nd cold temps have a ton to do with traction and 3rd you went with a smaller side profile which has less give in it then a taller side profile,again hurting traction.i think what your main problem here is the cold.

 

[twistedwankel]

Ok, I just upgraded the rear tires on my mildly modified 91 GT. I went from worn out 245-45-17 Goodyear Eagle ZR Gatorbacks to 275-40-17 Kumho Ecsta Supra 712s.

I'm wondering how much the COLD temperatures have to do with the Kumho's compound. I'm thinking since the temps have here (Dayton, Ohio area) have been below 25 degrees (the last few weeks) that the rubber has become HARD and therefore giving LESS traction.

IDEAS ????

As has been repeatedly mentioned all ready - and you figured out yourself. "Summer" hi performance tires have the same grip as ice below 40 degrees and are dangerous.

Also a bald tire has 100% surface contact and zero tread squirm.

Also remember with a lower profile/ wider tire you have to reduce the tire pressure to keep the tread flat and not riding on the crown. Probably 5psi in your case?

You definately need an extra set of wheels with ALL Weather traction rating for 4 months/year in OH winters. Or put your nice car away and drive an old Asian fwd beater for those bad months

 

[Katmandu]

As has been repeatedly mentioned all ready - and you figured out yourself. "Summer" hi performance tires have the same grip as ice below 40 degrees and are dangerous.

Also a bald tire has 100% surface contact and zero tread squirm.

Also remember with a lower profile/ wider tire you have to reduce the tire pressure to keep the tread flat and not riding on the crown. Probably 5psi in your case?

You definately need an extra set of wheels with ALL Weather traction rating for 4 months/year in OH winters. Or put your nice car away and drive an old Asian fwd beater for those bad months

Roger that.

Well, they are on 8" Cobra Rs which probably makes it worse off.

I dropped the pressure down to 28lbs and it did help a bit.

They car does not get driven in the rain/snow. Only driven when it's dry outside.

I probably should of gone with a 255/45-17 huh ? I wanted to go as FAT as possible though.

 

[twistedwankel]

Roger that.

Well, they are on 8" Cobra Rs which probably makes it worse off.

I dropped the pressure down to 28lbs and it did help a bit.

They car does not get driven in the rain/snow. Only driven when it's dry outside.

I probably should of gone with a 255/45-17 huh ? I wanted to go as FAT as possible though.

If the tire is approved for an 8" wide rim it isn't an issue unless the tire rubs on the body or strut? I used to run only 24psi cold in my 265mm wide tires if that helps? I once ran a tire not approved for my rims by only 20mm due to a misprint on the tire application chart from Goodyear. It was a real bastard for the guys in the tire shops to get the stiff racing tires on but they really performed well all the same and never had any issues with them other than getting them on and off the rims.

Once the weather is hot and you get your tire pressures correct they will probably hookup fine.

For what it's worth a 245mm tire on a 9" (rear) rim hangs straight down and looks stupid so I went to 265 so the wheel bead wouldn't get curb rash and they also looked better with a little bulge. So at least your "meats" probably look "mean" on those 8" rims.

 

[67coupe]

Are the tires new? If so, all tires come with some mold release still on them. They will have bad traction till the mold release wears off. How many miles are on the new tires?

I have Khumo Esxta MX's. 255/45 17 and I love them (second set). Very sticky in all weather conditions. I cut consistent 1.95 sixty foot times at the drag strip.

 

[85_SS_302_Coupe]

I've got Khumo Ecsta Supras on my Ponys and they grip less than the cheap Pep Boys 265s i used to buy. If i hadn't got them super cheap from a friend i'd be pissed.

 

[stang&2Birds]

Two things:
o What part of summer performance tire family wasn't clear?

o Second, I just ordered a pair of summer tires from tirerack. So, I know that tirerack made sure that you knew that the tires were not meant for the winter or cold weather.

Sorry, especially with the anal people at tirerack, there is no excuse to complain about not having traction in sub 50F weather with those tires.

I know, I have RE730s - an ultra performance *summer* tire. Below 50F, traction is questionable. Below 40F, they are joke on the road. Below 30F, it's down right dangerous to be using them on the road.

Tirerack is *very good* about giving proper info on their website so that people know what they are buying. It's not like you went to another website that just lists the tires, and maybe a picture.

 

[stang&2Birds]

ARGG, when will Stangnet fing the ****ing locations of the edit/quote buttons?

 

[85_SS_302_Coupe]

Umm...i don't know if that was directed towards me or not but mine suck in 90 degree heat just as bad as they do in 20 degree heat and everything in between.

 

[stang&2Birds]

Umm...i don't know if that was directed towards me or not but mine suck in 90 degree heat just as bad as they do in 20 degree heat and everything in between.

No, I don't know how good that Khumo tire is, or any Khumo tire is. My comment is that when people buy a *summer* tire, especially from tirerack, they know that the tire is for only the summer/warm weather.

 

[Mustang5L5]

If they are a summer compound then, yes, the temp will have a lot to do with it. My Eagle GS-D3s even came with a warning that driving them in sub-freezing temperatures could be dangerous. That said, I agree that Kumhos are crap and I wouldn't run them if you gave them to me.

+1 I have Kumho 712's on my Fox. They suck!


Plus like said, they are a summer only compound, so under 40 degrees they lose traction VERY easily and it makes them suck even more. They even recommend not ot drive in temps under 40 with them.


I'm actually driving right now on summer only Bridgestone Potenza S-03's In the summer, when it's 80 they grab like glue...but this winter where it was 20 degrees today, i can spin them in 4th if i'm not careful.

I've pretty much ONLY driven on summer tires in the winter. It can be done, but you really need to drive like you are on ice even on a dry day. That mean taking your foot out of the throttle in turns, avoid going WOT aburptly or at all, and braking smoothly.

I would hate to be in a car with someone totally unaware they are driving with summer-only tires on a nice 5 degree day.


It does make it easy to impress people by getting sideways in 4th at 20MPH

 

[talladam]

I know with winter driving, the narrower the tire = the better. More weight per square inch of tire that is contacting the road. Wider tires float easier, hence they break loose easier.

 

[85_SS_302_Coupe]

I know with winter driving, the narrower the tire = the better. More weight per square inch of tire that is contacting the road. Wider tires float easier, hence they break loose easier.

Yeah this is a WRC lesson. If you ever look at a rally car set up for snow, aside from being studded to hell and back they're very skinning, like Weld Draglite skinny.

Think of snow tires the way you think of snow shoes. Snow shoes give you a much larger footprint to displace your weight over a larger area. Wide tires on a car do the same thing as snow shoes on a person.

Right now my Merkur has 195/50/15 Blizzacks on it and i can drive it damn near anywhere unless i'm on ice.

 

[Mr. Rustypwnz]

I had those on my 86gt and they would spin like a mofo...

 

[lang williams]

I didn't like the 712's either, the ride was rough, an traction wasn't very good. I had 225/55/16 up front an 245/50/16 rear. I put the kumho AST's on my focus an they're better than the stock pirelli's in the winter.

 

[Mustang5L5]

I know with winter driving, the narrower the tire = the better. More weight per square inch of tire that is contacting the road. Wider tires float easier, hence they break loose easier.

Also why wider tires tend to hydroplane easier.

The weight is spread out over a larger area so it's easier to lift the tire off the pavement

 

[SVT32VDOHC]

Everybody covered you well. Different compounds between different brands, and the cool weather doesn't help either. Wait til she warms up a few degrees and take er for another spin.