Tire emergency

[Wayne7]

I gotta order tires I have kuhmo ecsta xs tires now in 275/40/17 front and 285/40/17 rear.
One of the rear has a cut accross the tread.
these are out of stick everywhere.
I am trying to be ready to go to my road course May18th.
So I was considering nitto nt05 in 275/40 or I can get the current kuhmo
ecsta xs in a 245/45 and put those on the front and put the good 275/40s on the back .
What would be the best option ?

[Bigblue73]

I'd run the 275/40/17's all around. Your are giving up 5/16" in overall tire height. Race on!

[Wayne7]

Thanks for the reply.
I am somwhat concerned mixing brands do you thinik the Nitto NT05 will match up well with the Kuhmo XS ?
Sucks the tire is not cut through to the cords. Its about 1/2 through the tread, but everyone that has looked says it looks they would be concerned on the road course. I was debating taking to the local tire shop but those guys are minimum wage tire changers so I don't know if Id feel any better even if they said it was fine.
Pictures of the damage.
http://i116.photobucket.com/albums/o...l/100_1944.jpg
http://i116.photobucket.com/albums/o...l/100_1941.jpg

[Ron.in.SoCal]

Conventional wisdom says don't mix brands/tread design front to rear, more so if you're planning on a road course. I was told this by a race shop shop when they noticed I bought a set of rears from the same manufacturer, diff tread style. Had no choice at the time, but was only driving on the street...

[Bigblue73]

Ron has a good point since the treadwear that is stated is based on the treadwear rating of the manufacturers line-up. Not a comparison between brands. XS is a 180 the NT-05 is a 200.

From a safety stand point - No way to running a cut tire on a road coarse. My luck would have my car in a crumpled ball of plastic and sheetmetal. I wouldn't want that happening to you either. I've heard good things about the NT-05 and it's a sticky tire.

[Jim Nilsen]

That tire will be a good spare for you and the set can be used at an autocross with low speeds and you can eat them up safely there. Don't discard it like it is no good for nothing. If you can afford another set of wheels it would be ideal but that is a lot of money.

The 275's all the way around will be a lot of tire for how good they hook. I run 285 Ecstas xs like yours all the way around and had no trouble hanging with anyone in the corners at several tracks. Just go with 275's unless you need to go with 200tw then you can join the rest of the trend that has been set.

[67rally]

There are some Kuhmo Ecsta XS 255/40/17's on ebay for $358 for the pair. You could put those up front and move your 275's to the rear. Probably the cheapest way out until the 285's are back in stock.

[Jim Nilsen]

If you have 275's up front, what size wheel do you have? 9"? 245's might be too small? and for a bit more info.... my 285 Kumho"s are the same section width as my 255 50 16" BFG's and the same diameter so be warned that another tire manufacture might not fit in some sizes even though they say they are the same. Kumho's can get you a lot more tread to the ground becuase of the flat sidewall.

[Norm Peterson]

What profiles for those 245 and 275 tires?

A 245/45 tire and a 275/40 tire are both mfr- and TRA-approved for fitment on 9" wide wheels. The 245 tire is the narrowest tire listed and the 275 is the widest (without looking into taller profile light truck/SUV tire sizes).

There is no problem with running tires out to or even slightly beyond the so-called "max rim width", other than individual appearance preference. I have 255/45 tires on 18 x 9.5 wheels (Mustang), 225/60 tires on 15 x 8.5 wheels (Malibu) and have run 185/70's on 13 x 7's in the distant past.

Running somewhat wider tires may increase ultimate grip and probably heat tolerance, but will sacrifice turn-in response and maybe a little precision in the process. For a 275/40 in a hard cornering application I'd really rather see 9.5" or 10" wheels, as the design rim width for that size is 9.5". Trade away a little ride quality to gain a little performance improvement.


I can provide some approximate comparative section plots (generated from tire size and wheel width information) that may help. These plots provide a closer sidewall shape than any of the online tire size comparison applications and do account for the effect of wheel width on tire section width.


Norm