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You are overly fixating on size, when construction and compound and tread pattern/treadblock stability are WAY more important.
I'm tellin' ya, you're going to get a much bigger improvement in handling feel going with a good Extreme Performance category tire than you will going from a 225/50-16 UHP summer tire that's highly rated for responsiveness within that category, to a 245/45-16 UHP summer tire that's an unknown (not tested or rated yet). It is possible that the wider T1R could feel softer/spongier than the Comp2s you have now.
Also, the 245 isn't going to put more tire on the road. Contact area is mostly independent of section width. Generally, a wider tire will have a wider/shorter contact patch. But in this case, the 245 might not even give a wider contact patch if both are mounted on an 8" wheel.
Anyway, again, specific tire construction/compound/tread pattern is going to be more of a driver of handling feel than 225/50-16 vs. 245/45-16.
ZDan, I won't argue with you, but the only way he'd really know which is better is to test them against each other back-to-back. And even w/o changing anything in the suspension, he'd have to do a sweep of tire pressures on both ends with both sets. Not likely to happen.
And tire size on a non-raced car is as much a subjective appearance thing as it is performance.
ZDan, I won't argue with you, but the only way he'd really know which is better is to test them against each other back-to-back. And even w/o changing anything in the suspension, he'd have to do a sweep of tire pressures on both ends with both sets. Not likely to happen.
It's exactly because that is not practical that it is useful to rely somewhat on good feedback from people with experience, objective test data, and "crowd wisdom" of survey results. You don't have to make a tire decision totally blind.
And tire size on a non-raced car is as much a subjective appearance thing as it is performance.
You don't have to track a car to want more responsive handling.
Here's what he said: "I was thinking that going wider - Wider Meaning more tire on the road will give me better handling - And more road feel - Quicker corners. "
If he wants these things, I think he will *definitely* get them going from his current UHP summer tires to a good Extreme Performance tire, whether 225/50-16 or 245/45-16.
He may or may not get them going from his current UHP summer tires (which are highly rated within the category for these characteristics), to a 245/45-16 Toyo T1R in the same category which we don't have test data or reviews to indicate where it falls in the "road feel" category.
I naively went from 205/50-17 UHP all-seasons to a different 215/45-17 tire in the same category on a Mazda3 and LOST all road feel and responsiveness and got a lot of obvious and unappreciated sidewall squishiness. Yech...
There are other factors which are WAY more important than 225/50-16 vs. 245/45-16 size as far as "better handling", "more road feel", and "quicker corners" are concerned.
Also worth noting that the 245/45-16 T1R isn't necessarily wider at the tread vs. Extreme Performance tires in 225/50-16.
245/45-16 T1R has 8.4" tread width.
245/45-16 RE11 has 9.1" tread width.
A lot of 225/50-16 Extreme Performance tires have about the SAME tread width as the 8.4" treadwidth 245/45-16 T1R:
225/50-16 RE11: 8.3"
225/50-16 Nexen NFERA SUR4: 8.4"
225/50-16 Hankook RS4: 8.3"
225/50-16 Yokohama AD08R: 8.5"
The Toyo T1R was released in February 2008....... Tire tech years are kind of like dog years, and those suckers have been around for nine years. Frankly splitting hairs on things like size doesn't matter much when you raise the white flag and go with tires that were mediocre during the Regan Administration
Still a good tire though. Yeah they grease up a bit in the afternoon, but in my experience they're always nice and predictable. For the money T1Rs are still much better than a mediocre tire for track days.
I run 245/45-16 Potenza tires, mine are the RE750 that are no longer available. In my humble opinion, if you've got stock 16 X 8 rims, the 245/45 is the perfect size. They just look bad-***, lol! Damn things are about 10" wide.
As noted, there currently aren't a lot of choices in this size, but there are enough to make it interesting.
Hence - As I get more tire on the road - How can I not get better handling and responsiveness on the road.
Not really getting more tire on the road, but rather changing the shape of the contact patch... But even if you were getting more contact patch area, friction force is in general not related to contact area. Adhesion force is, but this is barely if at all applicable for a UHP (i.e., not particularly performance-oriented tire) on the street. For hot gummy tires at the track, that aspect is a lot more apparent.
Car and Driver tested tires on a Golf GTI years ago, same tire make/model (Goodyear Eagle GT UHP all-season), same treadwear rating, same speed rating in three different sizes. Effects of Upsized Wheels and Tires Tested - Tech Dept. - Car and Driver
Skidpad results:
195/65-15: 0.83 g
205/55-16: 0.85 g
225/45-17: 0.85 g
Overall increase of only 2.4 % going from 195/65-15 to 225/45-17, a 15% increase in width.
NO increase in lateral grip going from 205/55-16 to 10% wider and lower-profile 225/45-17.
They also tested a different version of the tire with a higher speed rating and lower treadwear rating (different compound and internal construction for higher performance) in still wider and lower-profile 18" and 19" sizes:
225/40-18: 0.89 g
235/35-19: 0.88 g
Here the wider, lower-profile tire has slightly reduced lateral grip.
But there was a 5% jump going from the lower speed-rated and higher treadwear-rated 225/45-17 to the higher speed-rated and lower treadwear-rated 225/40-18 without any width increase.
Conclusions: Tire size barely if at all affects lateral grip for lower-performance UHP tires on the street, tire construction and compound have a MUCH bigger impact on grip than size.
... But even if you were getting more contact patch area, friction force is in general not related to contact area. Adhesion force is, but this is barely if at all applicable for a UHP (i.e., not particularly performance-oriented tire) on the street. For hot gummy tires at the track, that aspect is a lot more apparent
I agree with most of your comments, but I must respectfully disagree with the above.
Any rubber's friction coefficient is lower when the contact pressure is higher. That is the basic fact which makes, among other things, tuning handling with swaybars and weight distribution possible.
From my handling presentation:
---------------------------------------------------------------------
Rubber friction coefficient decreases as contact pressure increases.
Therefore:
Tire friction coefficient decreases as tire load increases
More weight transfer = less grip
Uneven tire footprint loading = less grip
Deviation from “critical damping” (excess dynamic load variation) = less grip : i.e., suspension friction, too much damping, too little damping = less grip
Everything that affects handling starts with these principles!
---------------------------------------------------------------------------
That also means that even with the same rubber compound and construction, a larger contact patch (assuming it is uniformly loaded) will increase grip.
As you said, a lot of other things factor into grip and driveability, but that does not change the relationship of contact pressure to coefficient of friction.
Also, the 245 isn't going to put more tire on the road. Contact area is mostly independent of section width. Generally, a wider tire will have a wider/shorter contact patch. But in this case, the 245 might not even give a wider contact patch if both are mounted on an 8" wheel.
This statement is from an alternative fact universe. A 245/45/16 tire has an almost identical circumference to a 225/50/16 tire. That being the case, the front to back tire patch will be the same. The 245 tire is wider, so the width of the tire patch must also be wider. If tire width doesnt matter, race cars would have skinny tires for better aerodynamics.
Your statement is ridiculous.
Originally Posted by ZDan
Anyway, again, specific tire construction/compound/tread pattern is going to be more of a driver of handling feel than 225/50-16 vs. 245/45-16.
While tire width does matter, this statement is also true. If you can get tire you want in a 245/45, that will be the better choice.
This statement is from an alternative fact universe. A 245/45/16 tire has an almost identical circumference to a 225/50/16 tire. That being the case, the front to back tire patch will be the same. The 245 tire is wider, so the width of the tire patch must also be wider. If tire width doesnt matter, race cars would have skinny tires for better aerodynamics....
Just one comment on this - within tires of similar construction, tire contact patch area is inverse to contact pressure. Contact pressure is also closely related to inflation pressure.
So, to increase the contact patch with a larger tire, one usually needs to reduce inflation pressure a bit.
Having said that, wear rate and tread heat generation is also related to contact-patch size and the length of time the tread contacts the ground, so a larger tread area (given equal compounds) will usually reduce wear rate.
Any rubber's friction coefficient is lower when the contact pressure is higher. That is the basic fact which makes, among other things, tuning handling with swaybars and weight distribution possible.
Yes, I know that grip does not go up linearly with load. I should have worded that differently...
Point was that for the *simplest* friction model area is not a factor at all. In the real world, it is a function of load, and increased load = increased area, but not as much increase in grip as grip per load is nonlinear.
That also means that even with the same rubber compound and construction, a larger contact patch (assuming it is uniformly loaded) will increase grip.
So, to increase the contact patch with a larger tire, one usually needs to reduce inflation pressure a bit.
Exactly, a wider tire at the same inflation pressure isn't necessarily going to *have* a larger contact patch. It could be smaller depending on tire construction and stiffness differences.
For DOT race tires on production cars, I've pretty much always run the same hot pressures for different size tires, generally aim for ~37 hot most of the time whatever the size...
This statement is from an alternative fact universe. A 245/45/16 tire has an almost identical circumference to a 225/50/16 tire. That being the case, the front to back tire patch will be the same.
Not necessarily... Imagine going way narrower with the same diameter. The contact patch can and does get longer as width goes down.
The 245 tire is wider, so the width of the tire patch must also be wider.
In general, but not necessarily! The contact patch seldom goes all the way from one edge of the tread to the other.
If tire width doesnt matter, race cars would have skinny tires for better aerodynamics.
Tire width DOES matter, but it's more to do with the shape of the contact patch under cornering loads and what that does to heat at the outer edge. A narrower tire will load and heat up the outer edge more quickly and lose grip.
A wider tire's contact patch under cornering load will generally not be as distorted and won't overload/overheat the outside edge as much.
That said, for UHP tires under street usage conditions, again there's little if anything in going from 225/50-16 to 245/45-16 (which I've done on the S2000 FWIW...)
While tire width does matter, this statement is also true. If you can get tire you want in a 245/45, that will be the better choice.
IMO for the usage, either choice is totally fine. WAY more selection in 225/50-16 though.
OP...I still recommend the 245/45's. They'll look better and perform as well or better on the street and fit just fine. And since car tech is also kind of like dog years, you raised the white flag along time ago by going with a car that's 25 years old. The T1R's will be just fine.
OP...I still recommend the 245/45's. They'll look better and perform as well or better on the street and fit just fine. And since car tech is also kind of like dog years, you raised the white flag along time ago by going with a car that's 25 years old. The T1R's will be just fine.
I'm running 245/45/16 on Toyo T1R's. They are fine, I can't compare to other tires yet since I haven't tried others.
...
A wider tire's contact patch under cornering load will generally not be as distorted and won't overload/overheat the outside edge as much....
That diagram is obviously a narrow tire with zero camber, which is of course your negative example. Anyway, I agree with what you said.
To add to what you said, other things remaining equal, a larger tire's shorter fore-aft footprint tends to result in less tire scrub during cornering. This means there will be less energy lost to heat while cornering with a wider tire, so exit speed will be greater. And exit speed is the "holy grail" everyone is searching for.
Last edited by DaveW; 02-15-17 at 02:31 PM.
Reason: Added 1st paragraph
They tested a Mustang with 255/40-19 UHP all season tires, then replaced one with the 155/60-18 space-saver spare tire at 60psi. Lateral grip went from 0.88g to an average of, get this, 0.87g.
spare at outside front: 0.84g
spare at inside front: 0.88g
spare at outside rear: 0.85g
spare at inside rear: 0.91g
Braking distance from 70 went from 172' to 173' with spare mounted up front, 174' with spare mounted in back.
0-60 suffered most, 4.8 went to 5.2 with spare mounted in back, due to different tire heights (that can't be good for the limited slip...).
Apparently they use sportbike rubber compounds for spares :P
Still, it goes to further show that for street performance, size just isn't that important...
02-09-17, 01:15 PM
