SZ50 replacement in 15"

[Q45tech]

Notice the new BFG g Force Sports come in 225/60/15 for $81340 AA A 96V @44 psi..............High Performance Summer.

At least it adds to the choices

After 1200 miles on the Kumho KH11 [just on the rear 40 psi] makes me appreciate the Milchelin Pilot H4 [235/60/15] on the front.

Tire Rack warned me that they were just barely Touring in the soft sidewall sense......seem adequate for $49 Summer tire. The nylon takes a set even in 70F overnight..........I can hardly wait till November to get them off the car..........they will only have 7,000 miles by then............great for Mom's car. Such are most of the 51 psi tires you inflate them [40-45 psi] to stiffen sidewalls and the impact harshness goes out of sight because the under tread section is so stiff.

Just like the old 35-36 psi max was a clue to performance sidewalls now 44 psi is the guide line.

[phenryiv1]

Sorry to sound like a n00b, but can you go over the psi information again? I think that I have it, but I may be waaaaaay off.

[Q45tech]

Just reminising about tires of yore.

Each tire construction is somehat different so you can't go by car tire placard pressure when you change tire models on car.

The 51 psi tires were created to improve rolling resistance [help with mpg] not to increase performance........with 51 psi tires the sidewalls are thinner more elastic [ballon like] and weaker from side impacts.........vs old fashioned 35 psi max tires which had some real beef [strength in sidewall] but couldn't expand.

Not sure I understand your question?

[phenryiv1]

Just reminising about tires of yore.

Each tire construction is somehat different so you can't go by car tire placard pressure when you change tire models on car.

The 51 psi tires were created to improve rolling resistance [help with mpg] not to increase performance........with 51 psi tires the sidewalls are thinner more elastic [ballon like] and weaker from side impacts.........vs old fashioned 35 psi max tires which had some real beef [strength in sidewall] but couldn't expand.

Not sure I understand your question?

Your last paragraph explained it perfectly. That was what I was asking for clarification on. I thought that that was what you were saying, but I was not sure.

Your statement on pressure plackards is the subject of much debate on other forums. I agree with you- when you change the max pressure of tires on a vehicle, you must either call the TIRE manufacturer or create SOTP guidelines regarding tire pressure, and can no longer simply rely on the car manufacturer's specs.

[maxnix]

Any idea where the BFG are produced? I imagine the Yen vs. Dollar appreciation killed the SZ 50EP as much as anything. They cetainly are not technologically obsolete.

Just noticed some SZ50 EP are again available at tire rack including the 245/50-16 size. No 225/60-15, though.

[SmithSR]

BFG now being part of Michelin Groupe..

A quick DOT code check against the production plant listing(lost my link to a great site with all plant codes worldwide ) would give you an exact answer to which country a given model line was produced in.

[Q45tech]

The psi on the car manufacturers placard is the ABSOLUTE MINIMUM safe inflation pressure not the maximun for the oem tire.

The question [when a Michelin is oem] and owner uses another tires [INFERIOR tire*] IS how much more than placard should be used.

* Proven fact in Industry is Michelin has the highest built in safety factor for load index vs heat due to the more expensive sidewall materials used by them. Their tires always last longer in the secretive 120% overload test vs inflation- ENDURANCE test after aging 2 year in heat.

A way around this is to change [other brand] tires prior to 20,000 miles or 2 years.........then endurances load/heat factors are relatively inconsequental.

http://ftp://ftp.nhtsa.dot.gov/Manufact ... /tires.htm

The front tires of a old Q with excess camber from wear is probably the finest endurance tester in existence. If a tire last 2 years in Phoenix............it will last anywhere.http://www-nrd.nhtsa.dot.gov/p...c.pdf

"The agency believes that RMA's inflation pressure values are too high for high speed testing because 1) they do not reflect values that are similar to the cold inflation pressures recommended by vehicle manufacturers, and 2) they do not correspond well with the real-world inflation pressures recently obtained from the vehicles measured during a recent NHTSA sponsored consumer tire pressure survey.[29]"

http://www.nhtsa.dot.gov/cars/...ref60

[qship96]

Based on q45techs above info and his comments on tire brands,question--why would any q45 owner NOT use the michelin pilots,especially in stock 15 inch,we are lucky they still make the 225& 235 60 15 in such a strong tire-------I say if we all buy these,maybe they will not abandon the tire in this size and we will have a good safe tire to keep our q on stock rims!

[szh]

One reason (to avoid it, that is) would be that the Pilot XGTV is a dangerous tire in wet weather, IMHO. I have had scary experiences with it - over more than one set of tires.

Note that the Pilot XGTH may be fine in this regard. I do not have any experience with it - but Dennis likes it.

Z

[szh]

Just noticed some SZ50 EP are again available at tire rack including the 245/50-16 size. No 225/60-15, though.

Two weeks ago, I happened to speak with Grant at Tirerack for an SZ50EP order for my wifes Acura (in a 205/6X-16 size) that they still had in stock and reluctantly decided against it for one simple reason. Grant only had 4 left literally and made a very pertinent statement: if one of these tires proved defective, he would not be able to replace it for me!

I ended up ordering another brand and model ...

Dang!

Z

[Q45tech]

Pretty naive to run any uni-directional tire beyond half worn if rain/wet performance is a criteria.........the very advantage of directionality disappears and the tires are sometimes worse than a plain old straight 5-6 groove tire assumming the same tread compound.

Why overall thru new to 3/32" the harder published 400 treadwear H4 may be better.......not better brand new but better from 6/32" down compared to the 300 V4.

[szh]

Agreed, Dennis! I try to change my tires at 4/32" - worst case - since I want good wet weather performance.

On my last Q, I went down a little further on the SZ50EP's (to about 2 - 3/32") since I was planning to replace the rims (to use 17" G35 rims) and just had not gotten around to doing that yet. When I installed the 17" rims, the car got new tires too - for obvious reasons!

On my wife's Acura, I changed the last time at 5/32" - more because of the length of time than the depth or mileage! The Michelins MXVs s that came with the car lasted >25k miles, but were clearly developing little micro-cracks (could see them in the grooves that did not touch the road) and I had a nail in the sidewall in one anyway.

This time, she still has about 5/32" on her current Goodyear GS-A tires (I do not like these tires, but the local dealer where I had to go to due to the nail) did not have any other ones in the right size. It has been three years now and these tires have always been very noisy and not particularly good at anything.

Z

[maxnix]

I personally prefer the XGTV marginally over the previous XGTH, which I notice have a new more aggressive tread pattern like the first generation I liked. I flip tires whether they are directional or not as part of my rotation, and it must be noted directional wheels will also demand flipping, even with non-directional tires.

All in all, if I had a chance to buy the last 4 SZ50 EP, and they spun up within specification at Tirerack, I would do it. They are the best combination of noise, wet and dry performance, ride and handling I have driven. The Michelins may be better built or have a stronger carcass, but for the first few thousand miles, they don't measure up to the SZ50 EP. In the wet, the Michelin XGTV are just not even in the same state, let alone the same ballpark, as the Firestones.

[phenryiv1]

Who makes these mythical tires- the SZ50?

[phenryiv1]

Based on q45techs above info and his comments on tire brands,question--why would any q45 owner NOT use the michelin pilots,especially in stock 15 inch,we are lucky they still make the 225& 235 60 15 in such a strong tire-------I say if we all buy these,maybe they will not abandon the tire in this size and we will have a good safe tire to keep our q on stock rims!

One simple reason- price. Also, most people do NOT realize the absolute importance of having the right tires on their vehicle. I have poo-poo tires on my I30 right now. It neve ceases to amaze me that people put crappy tires on a nice car. Look in the average parking lot- most of the tires were bought based on being the cheapest tire in the proper size- and some not even that!

The last 2 vehicles that i have bought have had tires that were a waste of money. As soon as I get my new rims cleaned up, I will be running new tires- and ones that are right for my intended uses.

[szh]

Who makes these mythical tires- the SZ50?

Firestone Firehawk SZ50EP.

Awesome tire!!! :ylsuper

But no longer available!

Z

[szh]

All in all, if I had a chance to buy the last 4 SZ50 EP, and they spun up within specification at Tirerack, I would do it.

Sigh ... it was a tough decision. The four tires were coming from two different Tirerack locations, probably had two different manufacturing dates and lots, etc. I would not have been able to spin them up before receiving them, and Grant could not assure me that he would be able to change one if it proved defective or (here is the clincher) if I wanted to replace one due to a driving mishap later on.Quote »They are the best combination of noise, wet and dry performance, ride and handling I have driven. The Michelins may be better built or have a stronger carcass, but for the first few thousand miles, they don't measure up to the SZ50 EP. In the wet, the Michelin XGTV are just not even in the same state, let alone the same ballpark, as the Firestones. [/quote]

TOTALLY agreed. :ylsuper

Z

[ddrumman]

Hey Q45 tech and the rest of the gang,

I’m still puzzled about what tire to get for my new 17x8 rims.

I thought that the following tire would be ok everything considered.BFGoodrich g-Force T/A KDW 255/45YR17 98Y SL 300 AA A 1653 lbs. 44 psi 10/32nds 8-9.5" 8.5" 10" 8.2" 26.1" 798798 $168However last time I posted Hitman told me that I should stay closer to 200.AA.A.

So I thought the Sumitomo HRZ II255/45WR17 98W SL 220 AA A 1653 lbs. 51 psi 10/32nds 8-9.5" 8.5" 10.3" 9.1" 26.1" 799799 $112

Less expensive and closer to the 200 AA.A. but with 51 psi.

What to do!!!

D.

[maxnix]

I would consider the Yokohama AVS dB S2. Call up tire rack and have them read the load information off an actual tire. I think it is a misprint on the website, as I have found other instances of incorrect postings of load ratings by them.

The Michelin sports would be great for an extra $70 per tire.

[ddrumman]

Hey Maxnix,

I wish man. Yokohamas are one of the first tires I checked out. Believe it or not, those db S2 specs from the tirerack are ACCURATE. If you go to the yokohama web site you’ll find the specs on a pdf file. Amazing.

Anyway, the Michelins are $70 extra of the $112 figure of the HTRZ IIs or the $168 of the BFGs?Also speaking of the topic: I can’t copy paste the link but there is an auction with TWO NICE ,FIRESTONE ,Firehawk SZ 50, 255/45/17,USED TIRES on ebay size 255/45/17 with a buy it now of $79.,If anyone is interested.

D.

[Q45tech]

Not sure one can trust tread wear index NOW as an indicator of tread compound softness! The use of Silicon additives has increased the wear ability of current newer tires. What use to be 150-170 now is likely a stamped 220-250.

The base [100 reference tire] has changed designs in many years

Why I like the tire rack wet/dry braking test.............notice some tires stop in 100+ feet, some in 90 and some in 80 feet.

Manufacturers have learned to modify compounds to cheat the less than 4,000 mile testing proceedure to yield a tread wear number that is not correlateable between brands and surely not useful in the real world.

That's why studying Tireracks test are so important and discounting some of owners comments.........especially the ones about how much better any new tire is than their old worn out ones.........they don't even realize what they type.

[texasoil]

It's another example of 'bean counters' and lawyers and MBA's figuring out how to squeak through the cracks in th eregulations. It would make a real nice class action lawsuit if we could show the tire manufacturer's were deliberately tweaking the compounding to max the test scores, knowing that real world consumer experience will suffer. Real hard to defend that to a jury. But might pass LEGAL muster and never get to trial.

[ddrumman]

That is so confusing. Shouldn’t there be a par level/standard that they all (tire companies) report to? How about a standard that allows us the buyers/consumers to compare all these different specs on an equal basis?That should be easy enough!!

D.

[maxnix]

Hey Q45 tech and the rest of the gang,

I’m still puzzled about what tire to get for my new 17x8 rims.

I would still read the actual sidewall of a P245/45R17 SZ50 EP. Even if it says 89Y on the chart, the 245/50-16 says 97 on the sidewall. Can't imagine it would fall off that much between the two sizes. Maybe Firestone didn't want to sell too many of them.

[texasoil]

Well there IS a standard-tires are compared to a 1960's quality bias ply tire. The regulations DO NOT require the tire to maintain the advertised performance and 'life expectancy' beyond the short duration test period. Hence, the trend to 'tweak' the tire compounds to max the test numbers and not worry about performance decay after that.

New testing methods under consideration would increase required performance (strength, peel resistance) in older tires. Problem is How to Test? Requires accelerated ageing tests, but what method? Everybody wants a level playing field tilted their way.