Spike - every car I've ever owned has had the normal tire pressure run between 32 and 36 psi. That's on all different sizes and brands of tires, all different makes of cars, everything from the Z to a crown vic and an astro van.

bdblackz believes in the theoretical, I believe in the practical real world reality. I understand his point of view and respect that. There's no argument that's going to change either of our minds though.

I predict that in 6 months, dada will be back to running at 35 psi instead of 42. He will discover unusual wear on his tires, he'll realize how hard the ride has become and will probably get a scare when he realizes how skittish the car behaves on rough ground in a turn.

 

Btw, it's not a case of "bdblackz believes this theoretical..." It's a case of all tire manufacturers, all governments, (hopefully most tire stores) know that this system works, and its based on real world testing. Sorry Dave, but it's not my mind that needs to be changed.

You still don't seem to understand this whole concept... if he runs his new tires at 42psi, they are going to mostly behave the same in those aspects as the stock ones at 35psi. If he runs the new ones at 35psi, it would be like running the stockers much lower... would you suggest he ran the stockers at 30? Why not?

 

I agree. Some people can “over-think” issues and make situations like this a lot more complicated than it should be, and in fact lose sight of reality.

I’ve been driving 45 years now, and believe that over-inflation of tires is a big mistake. Doing this makes the car handle poorly, and results in excessive and poor tire wear. 42 psi is too high a value for the Z. There is no car manufacturer or it's OEM tire supplier that recommends this psi.

I do respect bdblackz’s opinion and encourage him to continue posting his argument, but I do think he is way wrong. Maybe he can provide some useful information (but he hasn't so far).

--Spike

 

Are you suggesting there is a universal standard in a very disjointed industry?

--Spike

 

You guys are a joke! I give up.

 

I have the name, number and contact details for the engineer at Falken, Im going to email him because all of you are making me nervous, I have to say though so far the 42 psi is so amazing on handling (even on turns), I have complete control. I havent noticed much wear in the center of the tire either, its quite amazing. Can someone succinctly craft an email that will ask the question with addressing the correct information?

See this dude from Holland's excel calculation, I guess a little of everything is right:

http://forum.miata.net/vb/showthread.php?t=348669

I am also nervous what to do when winter starts here in NJ, I dont have an extra set of wheels with snow tires, should I drive the Z cold weather with the Falken 452s or is it just snow and ice I have to worry about?

 

The Falken 452 is a summer performance tire. It’s designed to run on warm roadways where it provides exceptional performance.

You cannot drive the Falken 452 on frozen roadways, on ice, or in snow. That won't work at all.

For your location, you need a winter set of wheels/tires.

--Spike

 

Excellent! I'm also a tire engineer so I'm glad somebody is taking the time to listen to those who actually know what they're talking about.

 

Any thoughts about running Falken 452's in NJ winters?

--Spike

 

You hit the nail on the head with your answer. I would fully advise against it also.

 

^^ Whew… we finally agree on at least something. Thanks for the reply.

Since New Jersey can get significant snow, and has ice often, I’m thinking studless snow tires for dada.

225/50-17” Front with 225/55-17” Rear is perfect.

But, I went with 225/55-17” all-square to allow rotating my winter wheel/tire setup. My car is equipped with VDC, so all-square was a concern. After running this setup for two seasons, I will say it works without any interference from VDC.

--Spike

 

Ill post the answer from Falken soon enough. But I took it a step further to lay this question to rest. I went to tirerack and found out who makes my tires in an XL and the same size. I found Continental, Pirelli and Hankook. There were others but I stuck to those three. I then emailed all three of them citing that I had the specific tire and gave them all the details. So now hopefully if I get 4 answers back we can see what the experts say. Good idea?

Sorry both of you, now someone can answer my question. I know I shouldnt drive my car in snow, ice but specifically on cold days with the sun out but no moisture, even if it hits 30F or below, is there a risk to drive my car with the falkens? Can I safely use these tires on dry but cold days in the east.

 

^^ The answer is: You cannot safely drive a Z with your summer performance Falken 452's during winter months in New Jersey. Sunshine at a cold (freezing) temp won't change this much.

Summer performance tires are down right dangerous running on frozen or near-frozen roadways. Ice and snow make it even worse (but frozen is already so bad adding more bad can hardly make it much worse than it already is).

You need to buy a set of studless snow tires if you want to run your Z during winter months in NJ.

--Spike

 

As Spike and bdblackz have said, summer performance tires are not appropriate for winter in NJ. It has very little to do with snow and ice. The compounds in summer performance tires simply don't do their job when the temps get south of 40 degrees (the specific temperature varies depending on who you ask). Summer performance compounds won't have safe grip or handling when cold. Even on a dry road.

I live in a moderate climate and I have other cars to drive when it gets cold. Even so, I'm going to be putting all season tires on my Z very soon. That way I can safely drive it on those cold dry days.

FWIW, I would never drive the Z in snow or ice even with snow tires. It just isn't worth it.

 

I GOT ONE RESPONSE ALREADY, DAMN IM CONFUSED...
------------------


What is normally done to calculate inflation pressures for plus sized wheels is as follows. We will take the original equipment size and vehicle recommended air pressure to calculate the corresponding optimal load. We then take the plus sized wheel and find a corresponding load to calculate the air pressure. This load is the limit that the vehicle manufacturer has deemed the limit the tire should carry. With XL tires, if you have a standard load tire and compare it to the same size with an XL rating, the XL tire will carry a heavier load. That does not mean you have to increase the air pressure, but it does follow a different load chart. What I did notice with your sizing is that your fronts are now a lower load carrying capacity than your original equipment tire. This is not what you want to do. We never recommend that you lower the load rating of a tire from the original equipment. I would recommend having your front tires replaced with a tire that will have an equal or higher load rating. As far as the rear tires, you can run the tires at 36 psi and increase it if needed to find the ideal performance desired. Please contact me if you have any questions.


Best regards,

XXXX X XXXXXX
Assistant Manager
Technical & Service Team
Hankook Tire America
1450 Valley Road, Wayne, NJ 07087
(973) XXX-XXXX
(973) XXX-XXXX fax

 

Dada - that's exactly what is described in the link I posted (Bridgestone's advice).

 

I know good call. But what about this load in the front, its only off by a slight amount, do I really need to change my tires now? I wrote to Hankook about this and this is what they wrote back:
--------------

Even though that tire is an XL tire, it is still rated to handle a lower load. This means that the tire will not handle the load that the vehicle is designed to operate under. This means that the tire will generate more heat even if the tire were inflated to its maximum. You can speak with Discount Tire Direct and explain to them what has been done. They should be able to understand that the tires are incorrectly on the vehicle.

---------------------
Spike others can you help me find a good set, I dont have my stock wheels so it will have to be a set, Tire rack is like $1300 for the cheapest set no TPMS.

Ill post more responses as they come along.

 

UPDATE, spoke to Falken directly, the guy there is a genius, sorry others our friend bdblackz is absolutely right. First he confirmed that the Hankook guy was partly right, DIscount tire gave me the wrong front tire, I was supposed to get 245/35/20 and they gave me 245/30/20, although it is a 64 psi difference with load, oem was able to handle 1356 and now I have 1323. WHy he said the Hankook guy was wrong is that the XL tire is supposed to handle more load not less.

On tire pressure, we spoke about the max load chart and what we have been saying here. He said that is exactly how every tire company and car company does it and in fact our oem tire at 35 is at the max load already. The XL tires does in fact carry more load and you have to increase the tire pressure to compensate for the size of the tire. Right now at 42 psi in my rear I can carry 1609 pounds (whereas OEM is 1565). In the front I can carry 1323 (whereas OEM is 1356). He repeated putting it at 42 psi is just the same as filling the original oem at 35 psi. He said if you want to be an exact match its 41 rear and 40 front but its more important to make sure you have the correct psi to remember and slightly higher is better than lower. He even said I will not get tread wear in the center and he said if the guys on the forum were right, go check you tire right now and tell me if you see more tread in the center, and I did and there wasnt. He said if i were to run the new tires at 35 or a little higher its like running the stock tires at a much lower PSI, again same concept echoed by bdblackz.

We will wait for the other experts to respond but looks like 42 psi it is for me and I have called discount tire, lets hope they replace my front tires for free.

 

Interesting thread, thanks to those participating. Ive been pondering this as well lately.

 

So how come you believe the Falken and Hankook engineers but not the Bridgestone engineer??