I've been told they grip like mad and wear the same way.

V

 

For Colorado seems like an all season tire is called for. The are quieter and last longer too.

 

I'll go with that and add that they do not survive in VERY hot conditions. My tyre guy says the Las Vegas heat and lack of humidity makes them crack on the sidewall like dryrot after 18 months here.

 

You touched on one of my pet peeves when it comes to the auto industry in general. The first one is the trend to go with larger and larger wheel diameters and less and less tire sidewalls. Result; bunch of bent wheels and rough ride over less than perfect surfaces with relatively minor practical improvements in general handling.

The second is the trend to put ultra high performance tires on many ordinary cars. I think the public is getting ripped off, being forced into buying expensive replacement tires every 10-12K miles. The rewards of such soft thread compounds over more durable compounds are so small that, I would bet, 99 percent of the driving public could not quantitatively sense it during their driving routines. The one percent that does sense it on public roads should be locked up :-).

IMO, there is no reason today that very high performance tires should not last 35-40K miles under normal driving for that 99 percent of drivers. For those who track their cars, they should have a set of wheels and race compound tires, separate from their street tires that are most certainly inferior to cheaper DOT race compounds.

On the other hand one of the worst decisions I had ever made was to put a set of DOT race "R" compound tires on my high performance street car. When cold, those tires were simply as slippery as if they were greased and no sane person could ever go fast enough and long enough on streets to put sufficient heat into them to start working.

Albert

 

I would dispute that from the experiences I had with a car some years ago. It came equipped with Goodyear GA tyres marked as "all season". It was not long before I ascertained that "GA" stood for "grip absent" in any weather, season or phase of the Moon. I think a hockey puck would feel like a feather pillow compared to those pieces of trash. I finally changed them for some hi-performance Kumhos and the difference was night and day. No more lock ups under moderate braking, no more stepping out at the back in slow corners at speeds that did not bother my SUV (!!!) and best of all, actual traction in the wet.

My local tyre shop could have tried to sell me new Dunlops or PS2s when I changed the rears on my XKR recently, but he flat out admitted that the PS2s rot and the Dunlops go like hockey pucks once they are half worn. You can get Sumitomos and Hankooks for half (or less) the price of the "premium" names and still get a high performance summer tyre. Do they have the ultimate performance of the name tyres? Maybe, maybe not. But I would put good money that they run rings round any no-season tyre, the ones marked all season for some strange reason. There is a very interesting tyre test on Car and Driver or Motortrend that compares different classes of tyre and the odd thing is that providing you do not live in a cold area, summers are the way to go.

 

I could not agree more with AXR6.

I have been driving high perf cars for over 40 years. This business of high perf tires has got completely out of hand as manufactures pander to the "boy racer" mentality with 155 mph cars.

My tire supplier will not even consider putting a lower speed rated tire on my car. "A 150 mph car has to have a 150 mph rated tire", he says for legal reasons, despite the fact I will never be over 80/90 mph. Well the fact is that super rated tires are not as safe for real world driving (in the wet, cold and snow) and I live in Florida. That same tire dealer will happily install Summer high perf "hockey puck" tires on cars that drive in cold conditions. And this does not even begin to address the practicality issues.

Hoo Boy. This ought to spin em up.

 

I believe what you are saying about that particular tire and do not have the answer why it would be that bad. Was it old where all the compound's softening chemicals were already evaporated or, was the tire abused, overheated? Perhaps or, perhaps it was just a bad tire.

On the other hand, I can tell you that in 1984 I won a season championship in an '83 Mustang in autocrossing on HR rated tires. I was up against all big bore cars, Corvettes, Shelbys, 911s, Jag XK etc. I would safely say that the cornering abilities of those HR tires were far higher than what just about ANY street driver would do today on their ultra high performance tires. That, because simply one can not push a car anywhere close to its limit on the street as you would normally on the track.

Those HR tires were rated for 130 MPH so, I am not suggesting to use HR rated carcass on a car that can do higher speeds. But, they could easily use the same thread compound that would provide all the handling a performance oriented street driver could ever want, plus give you about 35-40K thread wear.

Also, if you look at race tire technology you realize that going to 20" wheels is unnecessary and crazy. On my full blown GT-class race cars and formula race car I was using 13" wheels with really tall sidewalls (look at Indycar or Nascar tire/sidewall ratios) and, guess what; they provide steering response and handling that a street tire can not even imagine.

Tall wheels are a fad, and a bad one, and super soft compound tires only benefit the tire makers that can make a killing by forcing the public into buying new sets of tires ever time they roll the car out of the garage.

Albert

 

But my 20" Senta's look HOT on my XK

 

20" Senta's ??

 

Well, sure, they do look cool, if you like that looks. I am kind of neutral to the look. Still, I told my dealer when I purchased my XK with the 19" wheels that I would gladly trade for 17" wheels which would add a full inch to the sidewall, making the ride much more compliant.

Also, on my third generation, '93 RX-7, one of the purest sportscar ever mass produced, the standard 16x8 wheels weighted 13 lbs each and the total wheel/tire package was 25 lbs. When I upgraded to 17x9.5 wheels all around with 275 wide tires, the wheels were 17 lbs each and the total tire/wheel was 29.5 lbs.

Try weighting a 20" wheel/tire combo. I really have not tried but my sense is that it would be close to 50 lbs. That, because they have to build those wheels like tanks to stand-up to the beatings they will take due to the short tire sidewalls. They also have to make the tires heavier, the sidewalls thicker, to reduce the amount of flex as you hit a pavement joints so you don't bend the wheels. The results are super heavy wheel packages, worse ride and still a lot of bent wheels.

Weight is the absolute worst killer of performance as it hurts at every stage of performance driving; it hurts braking, accelerating and cornering. The worst place to add weight is "unsprung weight" in the wheels of car. So, we are giving up a hell of a lot of performance, comfort and increase the potential for expensive wheel damage, all for the "look".

I'd be most happy with a set of 17" max on my Jag. The only reason I did not go in that direction is that they repaved almost the whole distance that I have to drive these days and the ride on the 19" combo is pretty decent over the new pavements. Before the repaving I painfully cursed my way through those 150 miles of broken pavement which my SUV, with its 16" wheels and tall tire sidewalls would just handle beautifully.

Albert

 

When I was shopping for my XK one of the negative factors influencing selection was a wheel up grade package. Big wheels add to unsprung weight, the ride suffers, the tires are more expensive and the you can bend them on speed bumps. Did I mention curb rash?

Besides, the 18" Venus wheels that came standard on 07 cars look IMHO pretty damn good. That's going some as Jag has a penchant for putting funny/awkward looking wheels on its base model cars.

I do agree that big wheels look good on our cars, within reason of course, but at what price?

 

 

Anyone know if the ECU can be reprogrammed for a different wheel diameter? Admittedly the 20's are huge.

However, as a counterpoint to some of the other comments, I'm a big fan of the soft rubber on cars with power. It's not the speed rating I'm concerned with, but how well it manages to hold the road in the twisties. And there's a big difference between a PS2 and a Ventus V12. I have the latter on a car right now and I've hated them since day 1. They're way too hard. yes, they lasted about 50% longer than Goodyear F1s or PS2s, but they slide too easy. For my 2 cents, I'll happily pay the extra for good grip. These toys are too pricey to rely on hard, slippery, non-grippy rubber. Especially with the ridiculous (sweet, sweet, terribly ridiculous) power these kitties have.

 

Kthrash,

Nothing looks as good as the "double 5 spoke" design. I had them on my XJR and miss them still.

 

I read this thread with great interest and have a foot in both camps. I certainly enjoy the look of the 20" Sentas on my 07XK coupe. They fill the wheel arch nicely but I certainly dont feel that I get a huge advantage in roadholding over a wheel/tire combo with a taller aspect ratio. For me ride and comfort are as important as outright grip. My 07 BMW 328i with stock 16" wheels and 205/55 bridgestones has as much grip as the Jag but rides the ruts, joints and other road defects much better. I'm an enthusiastic driver but at some point I have to cruise down the freeway and that's proportionately a much bigger % of my time behind the wheel than throwing it around corners. I'm sure road noise would be reduced further with a deeper sidewall. For me a 55 aspect ratio is just about right as a balance between ride and roadholding. I know others will disagree. This is a very personal topic.

However, I think we have to respect axr6's comments and his experience having put fairly tall tires through their paces on the track and concluded that there is no real advantage to ultra low profile tires. I agree and I agree with the comment that we are being ripped off. Having to replace V rated tires on a Toyota Camry coz that's the OEM is BS. I needed 2 new tires for my wifes Lexus RX350 as we'd not rotated them. The fronts are way down but the backs are around 70%. Tire fitter required me to sign a waiver stating that the different tread depths could ruin the gear box and differentials - give me a break!!!! Yet another scam to make you feel guilty and buy 4 new tires.

In conclusion I put Sumitomo HTR Z III's on my XK and so far so good. Definately smoother and quieter than the original Dunlops and to me no loss of grip. Wet traction seems fine also. No hydroplaning (main issue for me in wet weather). Also I dont try to push it too hard in the wet - what's the point!

Steve

 

I will admit it is a refreshing relief to see so many here that actually understand suspension dynamics and a realization that the "big rim" world is in fact controlled by the Marketing Department, not the Engineers. Big rims generate sales numbers. Marketing has to spin the tale of "performance" to capture those on the fence. "Big Brakes (can you say "higher unsprung weight"?) can follow a very similar marketing theme. In the end it is the tire and its contact patch to the ground that does the stopping, not the brakes.

As axr6 points out, unsprung weight is a killer, as is the tires inability to conform and mold itself to the road imperfections and contours.

I don't doubt that somewhere out there in millionaire-land there is a car with big titanium rims and custom sticky tires at ten-grand a corner that will weight a paltry 35 lbs, mated to ceramic rotors that will dance circles around the combos we are debating here. Sadly I don't get to play in that world.

I do disagree with arx6 about his view of soft vs hard compounds, only because I always expect the most from my cars in any given situation. Whether I'm running my favorite canyon twisties (did I understand he wants me in jail?) or in town where a 5 year old suddenly tricycles out from behind a parked minivan. These are times when I have no regrets for spending the extra money to make sure I stop 5 feet short of the child instead of on top of him.
A 45k mile tire is a "Jack of all Trades", and does nothing well.

agentorange also brings up the comparison between summer and all-season compounds, and I fully agree that all-seasons are a poor option for any car enthusiast. The key here is temperature. Summer tires will outperform all-seasons right down to just before the temps approach freezing, so at that time you should swap on your winter tires that remain pliable at below freezing temps. In my opinion this is really the only true way to consider tires, but again I dislike compromise.

Vince

 

Hey Vince

Relax; no jail for you if its up to me :-). I've probably been a worse little boy than you were when it comes to driving slightly over the speed limits. Of course this is not admission of guilt, simply "making up a good story"...

Heck, I'd rather have your company carving up my local canyon roads when I'm in my 500HP, 2600 lbs fully race suspensioned third gen. RX-7, running on those 17x9.5 wheels with Sumitomo 275s installed. Killer combo! I do not have many staights near me, the longest being perhaps a third of a mile between tight corners but, I regularly hit 140 MPH between turns. My old friend, a Sheriff at a neighboring county gave me his friendly advice, thus:

"Albert, if a cop is trying to stop you when you do 140 MPH, don't stop! If you do, he will HAVE TO make you lie face down, handcuff you and book you for some kind of criminal felony violation."

So, I told him that I would not change my habits of not stopping. But, altogether I must say, I fear hitting a deer at those speeds far more than meeting a cop.

Regarding having the best and greatest; well it could be reassuring but, in reality I would venture to say that very very few people would be able to tell the difference between a tire that was tested on the skidpad at .95g and one that was .85g while doing blind street testing. Yet, the .85 g tire would last a lot longer. In my truly wild (past) days I have done some serious canyon racing against everything that existed, including top super bikes. When testing temperatures following a super fast run, the tires would never come up to anything close to what an average lap would produce at a race track, such as Laguna Seca or Sears Point. Because, no matter how wild I drove in those canyon contests, I always left something in reserve for the unexpected. Thus, I NEVER even came close to crashing on the street. My superfast drives were still well within the limits that a harder compound (0.85g) tire could easily handle. Not to brag but, the only canyon encounter I had ever lost was when I put on those R rated DOT compound race tires and they simply never accumulated the needed heat to make them work. They scared the living daylight out of me.

On the race track you leave nothing in reserve, if you do, they pass you. Thus, there you need a tire with the max G and you will still crash quite regularly, which is why I finally learned to stop using street cars on race tracks after crashing a Lamborghini and a totaling my first 3rd-gen RX-7.

While I know this is a Jag forum, hope I will be excused for posting pictures of my mere mortal present, 500 HP RX-7. I know true enthusiasts will appreciate looking at it.

Best of luck canyon carving and stay SAFE!

Albert

 

Al;

That is a very beautiful RX7.....I remember when they came out and all the Car Reviews complained that the torque curve was flat....across the whole range of RPM and so there were no grunt and go points in acceleration....I just laughed, they had been trying to build an engine that smooth for a 100 years and when they got one they complained.

Have to agree with the race guys here even with my limited track time, and the general trend to High Dollar Tires vs. performance gain and longevity.

Over here this is made worse by no Wear Ratings on Tires, very few all season options, useful for the Alps here. Many folks run winter tires all year because they last longer than summer tires.

Most folks here are convinced they have to have two sets of tires, Summer and Winter. With atrociously low mileage for nearly everything in the Summer category.

Amusing to read reviews by owners who are ecstatic that they got 8-10,000 miles from a set of tires before they had to replace them

Allow me to add to this discussion the inanity of low profile Run Flat Tires and the horrific ride they give. Had factory spec Potenza's on the MINI S the first two years...and the ITSMW and I would nearly be in fights about every pot hole she hit...with the buckboard ride knocking my teeth out. They are hard to miss over here since they are always in the drive line if you stay on your side of the road...took three or four shops before I found one that would put the 'illegal' regular tires on and toss a can Fix-Flat in the back.

Should mention here that the run flats tend to have more flats than the 'regular' tires and are priced substantially higher.

The switch to the three season Falken's, I say that because though they are supposed to be all season they are no good in the snow, with a higher profile, transformed the car into one that was pleasant to drive and about four times quieter on any road surface.

I should confess here that I did get a set of 15 inch wheels and winter Michelin's vs the 17 inch standard wheels for the MINI S for the wife...still have to switch off the DSC to get up the hill in the snow.

And yes the Falkens trade off from the Mongoose quick handling of the Potenzas to something that is only Cat-like was noticeable to me but not the wife. But it will still out handle and out corner in the mountains, literally behind the house, the XKR, with 20" Detroit's and factory spec Pirelli's.

I always advise friends getting new cars to pass on the run flat optional tires if at all possible and they all thank me when they test drive both versions.

Being a life long fan of the progressive handling of Michelin's in all weather, superb braking, and the very progressive and controllable breakaway of them I would always choose those as an all around go to tire.

That said I am coming around to the Korean and Japanese tires especially over here at a third of the price for what is comparable performance to the legacy brands and nearly three times the mileage.

I will certainly be looking for them as replacements on the XKR....while I am a devotee of having the right high speed tire and have been in "the back of the police car" more than once from testing them (there is a huge difference between getting a ticket and getting convicted ;-}, always talked my way out of those) and even with some pretty wide open spaces in Europe to test them as well I am not wedded to the necessity of matching unusable top speed to tires.....a little mental discipline is after all needed just to drive at all so why not add the 'speed limiter' to the right foot.

Course being men we all know we can drink more, make better love, and drive faster than the next guy so most of us on this forum with these cars will be saying 'wimp'.

No worries, two out of three isn't bad, and I can always pull out the Mini to pass you in the corners.

cheers,

jj

 

jj

Good to hear from someone from the gorgeous Alps. I love the Alps. Spent a fair amount of time criss crossing the Austrian Alps, playing Mario Andretti against hordes of Niki Laudas :-). I remember once renting the high performance version of the Opel Senator and racing a BMW Alpina all the way from the summit of Glossglockner (Spelling ?). Had my wife and best friend in my car and we finally passed the Alpina as he braked late and ran wide in one of the switchbacks. He was besides himself, shaking his fist out the window in anger at the audacity of an Opel even trying to keep up with the Alpina. Ha..ha..ha...

On the German autobahns, I felt like a kid in a candy store. The Senator would do a solid 240KM/hour (150MPH) all day long, which is exactly what I was doing while there. Occassionally my wife would act as an alarm siren telling me that we were going "too fast". I would remind her that, "Honey, believe it, or not, it is LEGAL here to go this fast. I basically nailed the accelerator to the floor for as much as the time as the traffic allowed it.

Yeah, the RX-7 had an incredible smooth torque delivery, credit to the dual turbo chargers where one kicked in for low RPM and the second came on for high RPMS. I modified all that, replaced much of everything, including injectors, engine computer with laptop programmable fuel curve, the turbos with much larger sizes, put them in parallel (non-sequential) so now, just like in a race car, no one is home under 3500 RPM. It starts waking there and when you hit 4500-5000 RPM all hell brakes loose all the way to 8000. That is when unsuspecting passengers would suddenly flail their bodies and arms while, trying to grab onto something, while instinctively calling out to their favorite dieties, such as: HOLLY JESUS FRIGGING CHRIST....!!!! It is, what I lovingly call, "violent acceleration".

I am all with you on the ridiculous stiffness of the run flat tires. I would not have one on any of my cars. In a way, the lower the sidewalls today, the more those low sidewalls are approaching run-flat stiffness. They simply can not afford to flex much because the rim is only a few cm from the road surface.

I have Sumitomos on my ultra high performance RX-7 and also put them on my previous, '05 Jag XK. I will not hesitate to use them again when my '08 tires will need replacing. Should not be long even though I only have about 5K miles on them now.... The point is that tires, such as Sumitomos HTRs may not be at the very top of the test specs when it comes to skidpad testing but, they are way good enough for even drastically fast street cornering and driving. They are less than half the costs of the "top spec" tires but the difference is so small in practical performance that can easily made up by slight differences in drivers skills.

Hope you're having a nice, snowy winter in the Alps. Here is CA we finally got a few inches of snow in the High Sierras last week, hardly enough to cover the slopes. Shaping up to be a bank-breaking season for the ski operators.

Albert