PAformula

iTrader: (1)

I took my car in yesterday for inspection and to get to front tires put on. I found a great deal on ebay for 2 z-rated dunlops. My back tires were only a yr old and I wanted to put these dunlops on the front. Since the back tires were v-rated the guys at the garage made a big stink about putting these on the front. I had them to it anyway, but they think there car will handle differently now and I will wreck the car an sue them. WTF? What do you guys think?

AlkyIROC

I really doubt you'll be driving at high enough sustained speeds for it to matter. Tire pressure won't increase in a Z rated tire unless you drive at sustained speeds over 118 mph. V rated tires are 100 mph. Short bursts over 100 mph is not considered sustained speeds.

http://www.tirerack.com/tires/tirete....jsp?techid=72

PAformula

iTrader: (1)

thats what I was thinking...

AlkyIROC

If you were racing in the Silver State Challenge, speed rated tires are required for specific classes because of the long distances traveled at a high rate of speed. For normal street driving, an H rated tire is more than good enough.

Higher rated tires means they won't heat up until higher speeds are reached. All street tires are designed not to heat up.

It still amazes me seeing people with street tires trying to heat them up in the water box at the drag strip. The rubber compounds are too hard to be heated up. Slicks are designed to heat up and the rubber gets sticky from the oils in the slicks when they get hot. Street tires don't have these oils.

What you have is fine. You'll never have a tire problem unless you run them low on air.

Zepher

iTrader: (1)

There is a pending lawsuit going on right now about putting on 2 new tires on the front,
here is the article, (I need to find the link to the one online.

AlkyIROC

It's always common practice to put new tires on the drive axle and if only 2 tires are installed, the better of the 4 remaining are installed on the other axle. The customer has the right to have tires installed on whatever axle they want. If the car needs 4 new tires and you can only afford 2, nobody can force you to buy 2 more tires or tell you what axle to install the new ones on.

If I had a vehicle that used 4 tires of all the same size, I'd want the new tires on the drive axle which for me would be the rear axle and if the old rears were in better condition than the fronts, have them installed on the front. When the front tires wear out, have the rears installed on the front and get new tires for the rear.

If it was a front wheel drive, new tires should go on the front and older tires go on the rear.

There is no law saying you have to install new tires on the front or rear. Nothing in the above story says if the vehicle was front or rear wheel drive. Since the new tires were installed on the front axle, I'd have to say it was probably front wheel drive like the majority of cars now so new tires on the front improve steering and traction.

I'd have to agree with Michelin. It was reported that the road wasn't wet enough to hydroplane. If the car had new tires on the front then the chance of any hydroplaning and losing control would drop dramatically. I'd agree and say it was driver error that caused the accident.

I used to work in a brake shop. We had all sorts of people complain about things after a brake job was done. "My transmission failed after you did a brake job. It must have been your fault" and many other excuses like that.

Guest

So how long before they tell us we have to replace all 4 at once?

rockit

iTrader: (3)

i can see that happening. "for your safety" they'll say, the other half they didn't type was "for your safety" "against your choice".

it's a matter of time until modified cars are banned from public streets to only tracks, then again the average hp of cars is going up REALLY fast soo.

Norm Peterson

PA's motor vehicle inspection code has something in it with respect to tire speed ratings, but I'm not entirely sure what it is. Probably either all 4 tires are supposed to have the same rating or they can't be less than whatever came as OE equipment on the car. My son-in-law used to have his PA inspector's license and might still remember even though he's been out of the repair business for a while.

The argument for putting the new tires on the rear is that full tread is normally more resistant to hydroplaning or sliding sideways in a wet corner, the assumption being that far more people lose control in the wet than in the dry. The front wheels you have (some) direct steering control over and in the worst case you simply go straight where you're pointed. But when the rear gets loose, it usually does so with less warning, the direction of the steering you need to use to catch the slide is usually at odds with the direction that your lane is taking, and the car can end up not "pointed" in the direction that it is traveling in. Applying the brakes (most peoples' normal reaction) only makes things worse when the tail starts to come around. This applies regardless of which wheels drive. And even when you are 100.00% fully aware that the rear end is going to come unstuck first, it will surprise you when it happens. BTDT, as the saying goes (no damage of any kind resulted, but when you clearly remember an event that happened over 40 years ago right down to being able to visualize the setting in a mental video, the point was hammered home pretty good).

All tires heat up during usage. On a warm day, my autocross tires will gain as much as 3 psi on the first 50 second run with speeds no greater than about 60 mph. And a psi or more on the next run as well. But tire pressures that are tied to speeds above the "V" rating of 149 mph involve inflation pressure settings, not pressure rises. I believe that in some cases there is also a reduction in load rating as well as a requirement for slightly higher inflation pressure. As already mentioned, that's a sustained condition, and is actually tied to a test procedure involving time durations at increasing speeds rather than a single brief spurt slightly above perhaps even the "H" rating of 130 mph.

There is the possibility that the "V" and the "Z" tires will handle slightly differently, as there is some difference in the intended usage, and there are differences among tire mfrs & tire models. It might be worth a little tire inflation pressure tuning to adjust the handling behavior and 'feel' to what you're comfortable with. Preferably at an autocross or similar off-street venue, though I think that a psi or so more in the rears than called for on the tire pressure sticker (with sticker inflation up front in those Z's) would be a step in the right direction for most street driving.


Norm