Are these tires going to be safe?
02-11-2005, 01:25 PM
#31
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I wonder if they have but just not listed in there. i was thinking of getting a set of the 225-45-17 for my fronts and 255-40-17 for the rear. I have the c2 rims. 7" front and 9 or 9.5" rear rims. I have to see if the 255 come in a 40 instead of the 45
02-11-2005, 01:46 PM
#32
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Jeff,
With that data, the tires you now have are clearly "H" speed rated - the DOT coding is very specific: the '96' is the load rating, the 'H' for speed: This tire will be safe at any speed you attain, but will lack the crisp performance edge in planting the rear in a corner, for example. Remember, the speed rating is determined for a sustained speed - hours & hours & ..., not a simple max. velocity beyond which the tire goes 'pop' ..... and confirmed under load on a test wheel/dynamometer for days until tire failure .... BANG!! Had our engineers do many tire tests - including destructive tests - although the ones on track were more fun: a guy can't delegate all the fun away ....
'fan4life' 255/40R17 is the rear you want ....
With that data, the tires you now have are clearly "H" speed rated - the DOT coding is very specific: the '96' is the load rating, the 'H' for speed: This tire will be safe at any speed you attain, but will lack the crisp performance edge in planting the rear in a corner, for example. Remember, the speed rating is determined for a sustained speed - hours & hours & ..., not a simple max. velocity beyond which the tire goes 'pop' ..... and confirmed under load on a test wheel/dynamometer for days until tire failure .... BANG!! Had our engineers do many tire tests - including destructive tests - although the ones on track were more fun: a guy can't delegate all the fun away ....
'fan4life' 255/40R17 is the rear you want ....
02-11-2005, 03:31 PM
#34
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Okay, all you tire and/or tyre experts. Riddle me this.
Our car's weight distribution is about 45% front 55% rear. The rear tires drive, but the fronts steer, requiring more sidewall strenth and more load rating. The size of the rear tire(which determines it's load rating) is larger than the size of our front tire.
Why?
All I can think of is esthetics. A Big Wheel in front would look comical, but would seem to be indcated by load and function.
Our car's weight distribution is about 45% front 55% rear. The rear tires drive, but the fronts steer, requiring more sidewall strenth and more load rating. The size of the rear tire(which determines it's load rating) is larger than the size of our front tire.
Why?
All I can think of is esthetics. A Big Wheel in front would look comical, but would seem to be indcated by load and function.
02-11-2005, 03:45 PM
#36
Supercharged
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I think I know the answer, but I can't think of a good way to descibe/illustrate it. But I think it's somehting like this, the rear you'd want larger to increase the patch with the road. With a larger patch, you can increase the amount of tourque applied to the wheels without breaking traction. THis is good for quicker acceleration. The fronts do not drive the car (this is the part I have difficulty 'splainin) as you pointed out. They steer the car kinda like a knife edge. You know what... nevermind, I just can't 'splain it very well. Probably has something to do with Physics and Vectors - 2 subjects that I didn't like.
Ooo! Ooo! Just thought of something. Dragsters! Big rears, skinny fronts. That's what you want. (But I still can't tell you why. Sorry.)
Ooo! Ooo! Just thought of something. Dragsters! Big rears, skinny fronts. That's what you want. (But I still can't tell you why. Sorry.)
02-11-2005, 03:52 PM
#37
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Wow, that's some nice shootin' Andrew.
I thought of the dragster analogy too, and the vast majority of the weight is on the rear. Also there is very little "steering" to be done once the hammer is down. Although I've seen videos from the cockpit that looks like he's driving down Lombard street.
Hey, I'll duel ya' for that 88 FS in the south.
Wonder what color it is?
I thought of the dragster analogy too, and the vast majority of the weight is on the rear. Also there is very little "steering" to be done once the hammer is down. Although I've seen videos from the cockpit that looks like he's driving down Lombard street.
Hey, I'll duel ya' for that 88 FS in the south.
Wonder what color it is?
02-11-2005, 04:03 PM
#38
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Well, I just got back from a good highway run on these tires. It felt horrible!! Car seemed to be floating/sliding in the rear. I get off the highway and right away I remember the guy who installed the tires saying that he set the pressure low and I could adjust it to how I liked. Blam! I put the backs at 42 (was at like 36) and the fronts I thought were at 35 - but they were loooow (around 28, I think). Time to throw away that pressure gauge I've been using.
Back on the highway and it was like night and day. Car felt like a new car. Crisp, responsive, picked-up faster, etc., etc. The tires seem fine. Had a quick run upto 180 klms and they felt great. Now, keep in mind - I had a set of completely bald Toyo Proxy's on the back (hence me not driving the car unless reallly needed) before and I'm guessing that didn't help. I owned a 944S just prior to this car and always found the 944 sooo much better in the handling department - not anymore; with the right pressure and good enough tires the 928 is comparable to the 944 (but still different).
I went back to the shop and all he had that I could put on were some Hercules Z-rated tires in the 225/50-16 size - same price as the ones I have ($325 Canadian for the pair, installed and balanced). I was going to get them, but stuck with the larger (245/50-16) in the back for now. They said they ordered in some Z-rated 245/45-16's and will give me a deal on them when they come in. I'm giving up a bit of speed-rating (and most likely some handling too) with the larger tires, but I have more width on the ground in the rear and they look nice, what with the larger sidewall. I did notice my speed is off a bit - according to a site, at 100 klms on my speedo - I should be going like 104, and I could kinda feel that a bit.
...but, all in all - these cheapy tires won't be too shabby for a month or so. Hey - if a World Class Runner has a pair of cheap sneakers on, it doesn't change the fact that he is still a World Class Runner - he just wouldn't compete in those shoes.
Back on the highway and it was like night and day. Car felt like a new car. Crisp, responsive, picked-up faster, etc., etc. The tires seem fine. Had a quick run upto 180 klms and they felt great. Now, keep in mind - I had a set of completely bald Toyo Proxy's on the back (hence me not driving the car unless reallly needed) before and I'm guessing that didn't help. I owned a 944S just prior to this car and always found the 944 sooo much better in the handling department - not anymore; with the right pressure and good enough tires the 928 is comparable to the 944 (but still different).
I went back to the shop and all he had that I could put on were some Hercules Z-rated tires in the 225/50-16 size - same price as the ones I have ($325 Canadian for the pair, installed and balanced). I was going to get them, but stuck with the larger (245/50-16) in the back for now. They said they ordered in some Z-rated 245/45-16's and will give me a deal on them when they come in. I'm giving up a bit of speed-rating (and most likely some handling too) with the larger tires, but I have more width on the ground in the rear and they look nice, what with the larger sidewall. I did notice my speed is off a bit - according to a site, at 100 klms on my speedo - I should be going like 104, and I could kinda feel that a bit.
...but, all in all - these cheapy tires won't be too shabby for a month or so. Hey - if a World Class Runner has a pair of cheap sneakers on, it doesn't change the fact that he is still a World Class Runner - he just wouldn't compete in those shoes.
