proper air pressure for 245/40/19 (2007 Infiniti M35 Sport)

[tooloon]

Anyone know the correct air pressure for the Bridgestone Potanza 245/40/19?

[szh]

(I am assuming that you are using this for a 2006+ M Sport wheel, but will ask the questions regardless. BTW, curiosity question: which Bridgestone Potenza tire specifically are you asking about - there are more than one tire models that have that name in it?)

1. What is the load index for the tire? If it is below 95, then you have too low a value for an M!

2. So ... are you using it on an M35/45?

3. In general, operating at about the pressure used for the load index calculations is probably the right place to start.

4. So, start by setting it at 36 psi and increase or lower it till you have the right compromise between road harshness and handling/performance and wear-n-tear.

5. Avoid going below 33 psi.

6. If you set it at 33 psi, please start a regimen of weekly checks (cold pressure, checked before you even drive 1 foot out of your garage, before the sun has a chance to warm the tire up, etc.) with an accurate pressure gauge.

7. If you set at 36 or higher, then you can check less often (maybe every 2 to 3 weeks), since the the normal drop over time will not be as serious a consequence if you are "low".

Z

[szh]

Also ... the thread title says 245/45-19, but the post says 245/40-19 ... which is it?

EDIT: Okay, thanks, I will fix the title!

Z

[tooloon]

Sorry, it is for an 2007 M35 Sport. I had the dealer replace the tires with the OE equipment. I can't recall the load index but they said they replaced them as per the OE tire.... Just curious

[szh]

Sorry, it is for an 2007 M35 Sport. I had the dealer replace the tires with the OE equipment. I can't recall the load index but they said they replaced them as per the OE tire.... Just curious

Ah! In that case, they probably put on Bridgestone Potenza RE050A tires in a 245/40-19 size (please check the tire and verify this though)! These are 94 load index, W speed-rated tires and the load load index is fine for your car (although I prefer a bit higher myself). Make sure that the date of manufacture (stamped on the sidewall - one side ... near the DOT label) is more recent than 12 months ... tires age even when just "sitting on the shelf"!

In any case, I would recommend that you set the pressure at 36 psi all around and see how you like it - the ride will be a tiny (mostly imperceptible) bit more harsh than running it at 33psi, but you will get a bit better handling, a bit better mileage, etc. Regardless, please check the pressure every 2 to 3 weeks and keep it at optimum.

One other comment: given that you are in Canada, I suspect that you get significant snow in the winters(?) These Bridgestone RE050A tires are simply not designed for snow use, or temperatures near or below freezing - they might even be downright dangerous at those temperatures (hard rubber and easy sliding). I'd strongly recommend that you get a set of cheapo wheels (in a 18x8, with 45 to 50mm offset size) and good snow tires in a 245/45-18 size for snow use.

Finally, while I am always in favor of keeping Infiniti dealer's happy (and getting good service as a result ), I would recommend that you find alternative sources for tires in the future. I suspect that it will almost certainly be much less painful for your pocket book! Not to make you feel bad, the exact same tire can be purchased from Tire Rack (www.tirerack.com) for a lot less than Infiiniti dealers - even with the shipping charges, local installation costs, etc., included. You can also often find sales at local tire shops that are decent prices (although perhaps not as good as Tire Rack prices).

Admittedly, it may seem like the convenience factor of getting it done at the dealer is worth it, but Tire Rack can even arrange to drop ship the tires to a local installer of your choice (select from their web site) and you don't have to receive the delivery and carry the tires to the installer, etc.

Z

[szh]

Also ... you have a 2007 M35 Sport with these tires. How many miles did you get out of the first set of tires that the car came with?

Z

[tooloon]

Thanks for the info. I will try 36 PSI. I notice the tire pressure fluxuate with the temps here since I got the car last week. I bought the car with 27800 miles on it and only two (rear) tires needed replacement. I suspect the previous owner (corporate lease return) didn't rotate.

I had the dealer replace all 4 tires so I could rotate them without issue. I paid $800 out the door for the tires installed. The dealer ate the rest of the cost. I knew there were better tires, I just didn't have time to research them and advise the dealer so I played it safe and had the dealer order the OE tire. I plan on going to a cheaper tire after these are finished. I'll have to research. Falken?

I plan on buying 4 snow tires in the fall. Anyone know if I can go to a 17" snow tire? Will there be an issue clearing the rotors? They would be cheaper then 18". Also, should I get a cheap alliuminum wheel instead of steel?

I bought the car in Chicago and imported it to Canada last week. I now have had it inspected and licenced here in Canada. Just had the windows tinted yesterday and it looks WAY better. I ordered the lip spoiler which is arriving today. Im now glad to be part of the M family!!!

Alex

[szh]

Actually, that is a darn good price for four of those tires (assuming it is Bridgestone Potenza RE050A ...)! So, yes, the dealer did eat some of the cost. Good!

On using 17" rims, I do not know for sure ... 18" wheels is likely to be a better fit (since the stock M has 18" rims and 245/45-18 tires) ... in case the rotors indeed do not clear or something! Whether it is Aluminum or Steel probably does not matter though, I'd think ... these are going to be beaten up in winter weather regardless. I used to get steel wheels for my cars when I lived in New England since they were cheaper.

Z

[maxnix]

I notice the tire pressure fluxuate with the temps

The word is fluctuate.

Read the Tire Rack website technical articles to learn how to read your side walls. When you mount tires, the sidewall information is rather llike the language in a contract you just signed. All the legal and technical notices reaquired by law are there.

[tooloon]

Thanks for the info! Yes, they were the Potanza RE 050A. I'm sure there are better tires, but I didn't have time to do the research so I told the dealer to buy 4 of the OE tires Iplay it safe).

Thanks,

Alex

[szh]

The Potenza RE050A are very good tires, so you do not need to worry about them.

Z