Mallory H.

My Bridgstones Turanza EL42 235 -50 -18 97V were replaced by the dealer with the Michelin 235-50-18 97H. I find this interesting as tire manufactures recommend that you not replace a tire with a lower speed rating, however you can go with a higher speed rating so it seems that the replacement tire should have been a 97V or 97W. Michelin does now have the Michelin Pilot HXMXM4 235-50- 18 97V so I am working with a tire dealer to see if we can work out a trade, I do not feel comfortable with an H rated tire on a car that came with a V rated tire. If a tire were to fail it would be interestingto see what the out come would be.
My dealer has also tried to steer me away from the transmission software up grade saying that it could affect gas milage but the TSIB does not say that gas milage will be affected so I think I will push for the upgrade.
I have no real issue with my LS460 other than getting the dealer to repair my car properly.

Craig B

Mallory, I'm going to have the transmission upgrade done as well as the wind noise retro fit on Tues. That sucks about them giving you the wrong tires. Who ordered the H rated tires? I would put their feet to the fire to replace them with the V rated Michelin's. I have the Dunlop's and will most likely keep them on until I wear them out unless there is a problem with them. They do have a stiff ride, but don't pull...

Good luck!

Craig

Luxofreak

First, he has to do whatever you ask. BUT... he isn't completely wrong, because the difference after this upgrade is that the torque converter DOES NOT disingage anymore after a complete stop in "D".

Without this upgrade there is disingagement which is the same as if the car was in Neutral.

After the upgrade, you will feel a little more vibration inside the car (trust me, almost nothing) and I believe it's a small price to pay to be free of the hickup from a dead stop.

Gas mileage will suffer a little if you're stuck in traffic all the time, because without the TC disingaged the engine is always under some load, even at idle.

I have this upgrade and I like it. The car is always ready to go. This, coupled with the wind noise fix they did makes the pursuit of perfection over IMO.

Johnny

A few months ago, Michelin did not have an equivalent size when I checked Costco's website. Now they have four different ones, all the way up to Z . So when you changed your tires, I thought you would get the exact equivalent, both in size and rating. It surprises me that the dealer (or Lexus?) would knowingly, or unknowingly pull a fast one like this. Or perhaps they really didn't know...

Your tranny update sounds interesting. I guess you could minimize the fuel consumption increase by temporarily shifting into Neutral at traffic stops...

Mallory H.

The tires are supposed to be what Lexus is recommending. The Michelin's are great and to me much better than the Bridgestones, I just do not understand their thinking on the speed rating. I believe that Lexus knows what they are doing but after the Ford Firestone incident, what would happen if someone were driving at a high rate of speed thinking that they had a V rated tire but instead they had an H rated tire and a tire failed ? Would the tire manufacture question why an H rated tire was on a car that originally had a V rated tire? If you look on the drivers door the tire sticker does not specify a speed rating so Lexus is ok there but on the window sticker it clearly states the tires are V speed rated and than with me it is a mental thing, an LS460 340 HP with an H speed rated tire.
God luck with the wind noise repair.

Johnny

You probably already know all this stuff, but I'm posting it for reference. Your H-rated tires are good for 130mph, and that in itself may end up being their position, since the car can barely exceed that. They probably fit V-rated tires standard as European cars can go faster, and since most of these standards originated there (higher speeds), Europe is arguably the benchmark used by foreign manufacters.

Speed Rating, Load Index & Service Descriptions (Source: Tirerack.com)

Using a P195/60R15 87S tire size as our example, the 87S at the end of the size represents the tire's service description. A service description identifies the tire's load index and speed rating. Service Descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991.

The first two digits (87S) represent the tire's load index and are followed by a single letter (87S) identifying the tire's speed rating.

Load Index

P195/60R15 87S - The load index (87) is the tire size's assigned numerical value used to compare relative load carrying capabilities. In the case of our example the 87 identifies the tires ability to carry approximately 1,201 pounds.

The higher the tire's load index number, the greater its load carrying capacity.

89 = 1,279 pounds
88 = 1,235 pounds
87 = 1,201 pounds
86 = 1,168 pounds
85 = 1,135 pounds

A tire with a higher load index than that of the Original Equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the Original Equipment tire indicates an equivalent load capacity. A tire with a lower load index than the Original Equipment tire indicates the tire does not equal the load capacity of the original.

Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 110.

Load Index Pounds Kilograms
Load Index Pounds Kilograms
71 761 345 91 1356 615
72 783 355 92 1389 630
73 805 365 93 1433 650
74 827 375 94 1477 670
75 853 387 95 1521 690
76 882 400 96 1565 710
77 908 412 97 1609 730
78 937 425 98 1653 750
79 963 437 99 1709 775
80 992 450 100 1764 800
81 1019 462 101 1819 825
82 1047 475 102 1874 850
83 1074 487 103 1929 875
84 1102 500 104 1984 900
85 1135 515 105 2039 925
86 1168 530 106 2094 950
87 1201 545 107 2149 975
88 1235 560 108 2205 1000
89 1279 580 109 2271 1030
90 1323 600 110 2337 1060


Speed Rating

In Europe, where selected highways do not have speed limits and high speed driving is permitted, speed ratings were established to match the speed capability of tires with the top speed capability of the vehicles to which they are applied. Speed ratings are established in kilometers per hour and subsequently converted to miles per hour (which explains why speed ratings appear established at "unusual" mile per hour increments). Despite the tire manufacturer's ability to manufacturer tires capable of high speeds, none of them recommend the use of their products in excess of legal speed limits.

Speed ratings are based on laboratory tests where the tire is pressed against a large diameter metal drum to reflect its appropriate load, and run at ever increasing speeds (in 6.2 mph steps in 10 minute increments) until the tire's required speed has been met.

It is important to note that speed ratings only apply to tires that have not been damaged, altered, under-inflated or overloaded. Additionally, most tire manufacturers maintain that a tire that has been cut or punctured no longer retains the tire manufacturer's original speed rating, even after being repaired because the tire manufacturer can't control the quality of the repair.

Over the years, tire speed rating symbols have been marked on tires in any of three ways shown in the following examples:

225/50SR16 225/50SR16 89S or 225/50R16 89S


Each of these was an acceptable method of identifying speed ratings.

Early tires had their speed rating symbol shown "within" the tire size, such as 225/50SR16. Tires using this type of branding were not to have been produced after 1991.

225/50SR16 112 mph, 180 km/h
225/50HR16 130, 210 km/h
225/50VR16 in excess of 130 mph, 210 km/h


Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire's service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:

M 81 mph 130 km/h
N 87 mph 140km/h Temporary Spare Tires
P 93 mph 150 km/h
Q 99 mph 160 km/h Studless & Studdable Winter Tires
R 106 mph 170 km/h H.D. Light Truck Tires
S 112 mph 180 km/h Family Sedans & Vans
T 118 mph 190 km/h Family Sedans & Vans
U 124 mph 200 km/h
H 130 mph 210 km/h Sport Sedans & Coupes
V 149 mph 240 km/h Sport Sedans, Coupes & Sports Cars


When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities.

W 168 mph 270 km/h Exotic Sports Cars
Y 186 mph 300 km/h Exotic Sports Cars


While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.

225/50ZR16 in excess of 149 mph, 240 km/h
205/45ZR17 88W 168 mph, 270 km/h
285/35ZR19 99Y 186 mph, 300 km/h


Most recently, when the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below:

285/35ZR19 99Y 186 mph, 300 km/h
285/35ZR19 (99Y) in excess of 186 mph, 300 km/h


As vehicles have increased their top speeds into Autobahn-only ranges, the tire speed ratings have evolved to better identify the tires capability, allowing drivers to match the speed of their tires with the top speed of their vehicle.

ghmundt

Did you have to pay for the Michelins or did the dealer swap them out for free? How many miles did you have on the Bridgestones?

dmvp29

As a friendly suggestion, I highly recommend that you look into getting Bridgestone Potenza RE960AS Pole Position tires as opposed to the Michelin Pilot HXMXM.

Here are some "surveyed response reviews" on both tires.

Michelin Pilot HXMXM: http://www.tirerack.com/tires/tires....l=Pilot+HX+MXM

Bridgestone Potenza RE960AS Pole Position: http://www.tirerack.com/tires/tires....+Pole+Position


As a benchmark, here are the reviews for the stock Bridgestone Turanza EL42 tires: http://www.tirerack.com/tires/tires....l=Turanza+EL42

The stock turanza EL42s have remarkably low ratings.


Edit:

Go to the main "survey page" here: http://www.tirerack.com/tires/surveyresults/index.jsp

Click on the type of tire you are looking for so you can view the averaged survey results in a neat, concise table. Pay close attention to the "total miles reported" column.

On a 1-10 scale (10 being the "best") I'd go with an 8 rating that has 21,000,000 miles vs. an 8.5 rating with only 2,000,000 miles reported.

ntran18

iTrader: (27)

Doesn't the LS have a speed limiter set to 130mph? If so then H rated tires wouldn't make much of a difference, right?

Mallory H.

The only tires that Bridgestone has in the 235-50-18 is the Turanza EL42 which comes as an H and V Speed rated tire and the Turanza Serenity which is a W speed rated tire.
It is not just the speed rating but higher speed rated tires also handle a little better than lower speed rated tires that is why I think the higer speed rated tires are used here in the USA, not so much for speed but handling.
The Michelins were put on at no charge to me and I think I had about 6000
miles on the car. I really like the Michelins and being that I have driven on Bridgestone and Dunlops to me the Michelin HXMXM4 is the better tire for this car.
The tire rack reviews and customer ratings are good but you must also look deeper into those reviews and ratings by the type of cars that the tires are on and also a Tire Rack road test may favor a tire that the customer reviews and rating may not favor as is the case with the Michelin HXMXM4 in its catagory the customer ratings places it at 16 but a Tire Rack road test ranks it better than the number 1 tire rated by the consumer.
I would like to thank everyone for their valuable input but will more and likely try and get the V rated Michelin.

thrang

What was the reason for the replacement? Was it proactive from their side, or in response to a certain complaint?

Thanks

Nospinzone

Re: TireRack customer ratings. I think you have to be very selective when reading them. I will go through the individual comments and pay attention to reviewers who more apparently know what they are talking about. Clearly some of reviewers are clueless. In other cases, some people rate the tire based on solely one criterion, e.g. tread wear. That's fine if that is what's important to them, just so long as they state that in the review.

Luxofreak

I agree.

You know, one of the best (if not the best of all) tires I ever installed on my cars is the goodyear F1-GS-D3 - this tire is super quiet, has amazing wet traction and looks really nice too.

When the time comes to swap tires that's the one I'll install on my LS-460.

Craig B

Thanks Mallory! I think the V rated tire has a stiffer sidewall. I am going to have the software upgrade done on the transmission as well. Are you just going to run the H rated tires, or try to have them replaced?

Good luck!

Craig

dsc07

That's very interesting, Luxo. I have exactly the opposite problem. When the torque converter disengages, I have engine vibration. However, if I use the brake hold feature (no torque disengage) it runs smoothly.

I'm taking my car in for 15k service tomrrow and will be asking for the upgrade as I can't stand the grabbing from stop.