[UnknownJinX]

Originally Posted by Msquared

I'm sure you know this, but an engine's peak power is rated at one RPM where it produced that peak power. If the engine is operating at a lower RPM than that, then it makes less power. I think you're missing the part about "at the same road speed." The engine cares very much about the gearing, because the overall gearing (including tire diameters) determines what RPM the engine is turning at for a given road speed. Consider that the entire purpose of a transmission in a performance setting is to keep the engine as close to peak-power RPM as possible! Again, if the LT1 with stock tires is turning, say 3000rpm at 20mph in 1st gear; then putting 1" taller tires will cause the engine to only turn 2892rpm at the same 20mph. Assuming the engine's torque output is the same at both RPM, then it is making 3.6% less power at 20mph due to the taller tires, and the car accelerates 3.6% less hard from 20mph.

The bottom line is that actual horsepower being applied to the road at the time (not the rated peak power) determines how fast a given mass can accelerate from a given road speed. Period. And yet again I point out that the tractive force that directly accelerates the car is purely dependent on road speed and power being applied to the contact patches. So if we agree the car is accelerating slower from a certain speed with the taller tires (which is really all that matters here), then we must also agree that the engine is making less power at that road speed. The physics demands that this must be so. It's not optional and it doesn't matter if someone disagrees with this or not: it is a fact that absolutely must be true or else physics stops working altogether.

Think about it this way. You correctly pointed out that power is a measure of how fast work gets done. A Camaro is a given amount of mass, and we want to move it (do the work of displacing it) as fast as possible. The faster this Camaro covers a set distance from a standing start or accelerates from one road speed to another, the more power it applied to the road during that interval. If we agree that it will do that work slower with taller tires, then we must agree that it applied less power to the ground over that interval as well, or else our definition of "power" is wrong (which it isn't).


I would tell you from experience that SC3s are not the tire of choice for trying to accelerate with a lot of power in a straight line. They actually kind of suck at that. So before trying to use taller tires and deal with all the tradeoffs I've discussed above, the very first thing I'd do is find tires that hook up better. That would make a world of difference, as opposed to taller tires that have far more negative effects than positive ones.


It's going fine. A debate is not intrinsically bad, and we can all learn from one another. Anyone who wants to can join in.

Well, sure, you miss out on some acceleration, but if you can hold out the slightly lower acceleration for slightly longer, it could be worth it. A taller tire will give you more top speed with the same gear ratio, don't forget that. That's the whole science behind gearing: you are compromising torque for top speed.

And focusing on that 3.6% of engine power difference doesn't make much sense when you could easily argue more about the moment of inertia of a bigger wheel/tire combo. A bigger tire will shift the mass towards the outside of the rim so it takes more to get it to accelerate angularly. And the moment of inertia is correlated to the distance of the mass to the centre squared, so yeah, shifting that mass to the outside isn't smart from that point of view.

Or if you are lazy, just use two words: unsprung mass. More is bad. There you go.


BTW SC3 is great for a dual-duty DD-track tire. There is definitely stickier stuff out there, but in terms of value, I'd argue that SC3 is definitely up there.

In general, I agree with Idaho here. That supercharged engine will have to worry about traction long, long before it has to worry about a slight drop in torque or a bit of increase in the moment of inertia of the wheel/tire combo. That's unless you somehow make a mid-engine or AWD Camaro, anyway.

[Msquared]

Originally Posted by Idaho2018GTPremium

An A10 ZL1 has 2.85 rear gears and is still quick. If it had 3.73s or something, it would shift way too much.

I forgot to comment on this. The A10 cars have the 2.85 rear gear because their transmission ratios are way, way shorter than the manual 6sp. For example, 1st gear in my manual is 2.66 and multiplied by my 3.73 final drive the total reduction is 9.92. Whereas the A10's 1st gear is 4.7, and with a 2.85 final drive the total reduction is 13.4! My 6sp's 1:1 ratio is 4th gear, like in most manuals, but the A10's 1:1 is 7th gear! In a quarter-mile drag run the 6sp car gets a little way into 4th gear, whereas the LT1 A10 will get almost all the way through 5th. So this is a real apples:oranges comparison, but I certainly agree one would not want to use even steeper gears in a typical A10 car on the street. For the drag strip, however, with a supercharger, it might be pretty interesting to try a 3.07 or 2.95 rear gear to try to use most/all of 6th before the lights (139mph at 6500rpm with a 2.96 gear). Again, keeping the engine as close as possible to peak-power RPM is the name of the game for 1/4-mile times. The manual 6-speed is set up really badly for that.

Originally Posted by UnknownJinX

Well, sure, you miss out on some acceleration, but if you can hold out the slightly lower acceleration for slightly longer, it could be worth it. A taller tire will give you more top speed with the same gear ratio, don't forget that.

It depends on the exact distance you and speed you are working with. For example, with an LT1 6-speed and LT1 tire size you get about 110mph at redline in 3rd gear, and you have to shift to 4th a little before the lights (typical trap speed of 115mph stock). It's possible that making the ratio taller to eliminate that shift to 4th would actually improve things overall. But you'd need about 1.5" more tire diameter, which means about 29.2". That's really tall and I'm not even sure that would fit in the wells without rubbing something. You'd probably be better off changing the rear gears to 3.45s and keeping the stock tire diameter.

But you'd be way faster going a lot steeper and using most of 4th gear too. So for instance, a 4.55 rear gear would get you 118mph and a much shorter time because you'd get a lot more average power output through the run than with just three gears used. If you supercharge the LT1, you probably want 4.11s so you can use most of 4th for a 130mph top speed. But with the stock 3.73, top speed in 4th is 144mph - way faster than you'll be going through the traps. So you definitely don't want taller tires with stock gears!

As noted above, with a supercharger and the A10 you also don't want to go taller because you can't use all of 6th as it is. Ideally you'd shorten the final drive to 2.95 or 3.07 so you could really wind out 6th through the lights. With 6 gears and the very fast shifting of that transmission, that engine could be held very close to peak-power through the whole run.

And focusing on that 3.6% of engine power difference doesn't make much sense when you could easily argue more about the moment of inertia of a bigger wheel/tire combo. A bigger tire will shift the mass towards the outside of the rim so it takes more to get it to accelerate angularly. And the moment of inertia is correlated to the distance of the mass to the centre squared, so yeah, shifting that mass to the outside isn't smart from that point of view.

I thought about adding that in, but the reality is that the added inertia is insignificant compared with the inertia of the car's 3800lb mass, even though it's rotating. I've done the math and it's a tiny fraction of a percentage point. It's nothing.

Or if you are lazy, just use two words: unsprung mass. More is bad. There you go.

I am lazy, and this is very true. However, unsprung mass doesn't really matter for drag racing, and Idaho completely discounted all of the many negative effects that taller tires have on handling. So I didn't bother.

BTW SC3 is great for a dual-duty DD-track tire. There is definitely stickier stuff out there, but in terms of value, I'd argue that SC3 is definitely up there.

I agree if we're talking about road course tracks. But again, Idaho completely discounted that and basically made this all about acceleration in a straight line. For that duty, the SC3 is pretty bad. There are plenty of drag radials that will obliterate it, and given where this discussion went those would be the only tires to consider. But even the Falken RT660 is way, way better at gripping in a straight line than the SC3.

In general, I agree with Idaho here. That supercharged engine will have to worry about traction long, long before it has to worry about a slight drop in torque or a bit of increase in the moment of inertia of the wheel/tire combo. That's unless you somehow make a mid-engine or AWD Camaro, anyway.

Again I agree, which is why the OP should strongly consider wider tires with much more forward grip than stock. But going to a 1" taller tire does almost nothing for traction, and hurts acceleration after the tires hook up even more than it helps the with traction. I'm saying that increasing tire diameter by itself is a net loss to for a 1/4-mile performance, which contradicts what Idaho claimed. If the OP is only concerned with improving straight-line traction after a big upgrade in power, then he needs to look at drag radials that are much stickier and wider than his current tires, and he'll need wider wheels to go with them.

For example, if he used Mickey Thompson ET Street tires in 325/35/18 on 18x11 wheels he'd probably double the grip he has on the stock all-seasons...literally. That tire happens to be about 3/4" shorter than the stock tire. With the 6sp manual it would give him 139mpoh in 4th gear, so he'd probably use most of that (after all the motor upgrades) which would be great. With the A10 (the OP never told which he has), he'd get 143mph in 6th, which is pretty good. With either transmission, you wouldn't want a taller tire for quarter-mile performance.

[UnknownJinX]

Originally Posted by Msquared

I forgot to comment on this. The A10 cars have the 2.85 rear gear because their transmission ratios are way, way shorter than the manual 6sp. For example, 1st gear in my manual is 2.66 and multiplied by my 3.73 final drive the total reduction is 9.92. Whereas the A10's 1st gear is 4.7, and with a 2.85 final drive the total reduction is 13.4! My 6sp's 1:1 ratio is 4th gear, like in most manuals, but the A10's 1:1 is 7th gear! In a quarter-mile drag run the 6sp car gets a little way into 4th gear, whereas the LT1 A10 will get almost all the way through 5th. So this is a real apples:oranges comparison, but I certainly agree one would not want to use even steeper gears in a typical A10 car on the street. For the drag strip, however, with a supercharger, it might be pretty interesting to try a 3.07 or 2.95 rear gear to try to use most/all of 6th before the lights (139mph at 6500rpm with a 2.96 gear). Again, keeping the engine as close as possible to peak-power RPM is the name of the game for 1/4-mile times. The manual 6-speed is set up really badly for that.


It depends on the exact distance you and speed you are working with. For example, with an LT1 6-speed and LT1 tire size you get about 110mph at redline in 3rd gear, and you have to shift to 4th a little before the lights (typical trap speed of 115mph stock). It's possible that making the ratio taller to eliminate that shift to 4th would actually improve things overall. But you'd need about 1.5" more tire diameter, which means about 29.2". That's really tall and I'm not even sure that would fit in the wells without rubbing something. You'd probably be better off changing the rear gears to 3.45s and keeping the stock tire diameter.

But you'd be way faster going a lot steeper and using most of 4th gear too. So for instance, a 4.55 rear gear would get you 118mph and a much shorter time because you'd get a lot more average power output through the run than with just three gears used. If you supercharge the LT1, you probably want 4.11s so you can use most of 4th for a 130mph top speed. But with the stock 3.73, top speed in 4th is 144mph - way faster than you'll be going through the traps. So you definitely don't want taller tires with stock gears!

As noted above, with a supercharger and the A10 you also don't want to go taller because you can't use all of 6th as it is. Ideally you'd shorten the final drive to 2.95 or 3.07 so you could really wind out 6th through the lights. With 6 gears and the very fast shifting of that transmission, that engine could be held very close to peak-power through the whole run.


I thought about adding that in, but the reality is that the added inertia is insignificant compared with the inertia of the car's 3800lb mass, even though it's rotating. I've done the math and it's a tiny fraction of a percentage point. It's nothing.


I am lazy, and this is very true. However, unsprung mass doesn't really matter for drag racing, and Idaho completely discounted all of the many negative effects that taller tires have on handling. So I didn't bother.


I agree if we're talking about road course tracks. But again, Idaho completely discounted that and basically made this all about acceleration in a straight line. For that duty, the SC3 is pretty bad. There are plenty of drag radials that will obliterate it, and given where this discussion went those would be the only tires to consider. But even the Falken RT660 is way, way better at gripping in a straight line than the SC3.


Again I agree, which is why the OP should strongly consider wider tires with much more forward grip than stock. But going to a 1" taller tire does almost nothing for traction, and hurts acceleration after the tires hook up even more than it helps the with traction. I'm saying that increasing tire diameter by itself is a net loss to for a 1/4-mile performance, which contradicts what Idaho claimed. If the OP is only concerned with improving straight-line traction after a big upgrade in power, then he needs to look at drag radials that are much stickier and wider than his current tires, and he'll need wider wheels to go with them.

For example, if he used Mickey Thompson ET Street tires in 325/35/18 on 18x11 wheels he'd probably double the grip he has on the stock all-seasons...literally. That tire happens to be about 3/4" shorter than the stock tire. With the 6sp manual it would give him 139mpoh in 4th gear, so he'd probably use most of that (after all the motor upgrades) which would be great. With the A10 (the OP never told which he has), he'd get 143mph in 6th, which is pretty good. With either transmission, you wouldn't want a taller tire for quarter-mile performance.

Assuming what Idaho said is true about the contact patch(the theory is sound, at least to me), I think it boils down to if you can get traction with the stock tire diameter. If you can, then that's the best-case scenario, but if not, then the taller tire diameter's larger contact patch could help. In that case, you want the tallest tire diameter that can give you just enough grip to go forward. It's just hard to say how large is too large.

But yeah, dedicated drag radials will likely solve the issue without the need to step up in the tire size. I just don't know if OP is going that far.

And here is something else to watch out for: if you go for drag radial, you might want to take a look at the strength of the rear diff and the half shafts coming out of it. My friend with a Hellcat Charger told me that there is a reason why Dodge didn't put very sticky tires on Hellcats. It's much better for you to burn the tires than break the diff or the shafts, as some people do indeed break their diff or shafts after switching to drag radials at the drag strip with their Hellcat.

[wnta1ss]

Originally Posted by CaptainChad

I know that my LT1 comes with a 6.2L V8 engine with 455 hp, so let's say I decide to get a Procharger D1SC installed and I want to be able to get the most performance out of it, and FYI I know there is more to it than just the tires, for the other stuff I'm figuring out what else I need to upgrade but for the sake of this post this is going to be tires.


So again if I get a Procharger D1SC installed, what kind of tires should I be looking at to get the most performance out of the supercharged engine? I know that the stock tires for the LT1 are P245/40R20 with +25mm offset on all sides. If I supercharge the engine, I'm assuming I should be looking at different tires possibly, you guys know a lot more about this than me so I would like to hear what your thoughts are on this. One other thing to think about is that the rim width and rim diameter on the stock LT1 is 8.5Jx20(J is the mounting flange type). I know the the camaro ss I believe is 9.5Jx20 in the front and 10Jx20in the rear (I believe).

If you are looking for acceleration traction for your soon-to-be supercharged power, look at the tire compounds, not just the sizes. I have 275/35 PS4S (300TW) on my stock SS 9.5 rear wheels and they can spin at under 60 with just a few bolt ons even. Also had some 305/30 SC3 tires on 11s and those spun at low speed surprisingly easily despite their 220TW rating. I did have a centrifugal blower in the past, and I did not bother racing that config without some drag radials. MT drag radials worked decent, and I ran in the 10s with them. But they are not so great for street driving, perhaps those new Nitto NT555RII might be a better compromise for street use while still having some acceleration grip due to their soft rubber (100TW)? They are a 'drag radial' but not as radical as some others are. If you are looking for a combination of both acceleration grip and cornering grip, then I hear that the Toyo R888R (road racing tire) works pretty well, though it's apparently got a lot of road noise to contend with.

[Crushin_LT1]

Originally Posted by wnta1ss

If you are looking for acceleration traction for your soon-to-be supercharged power, look at the tire compounds, not just the sizes. I have 275/35 PS4S (300TW) on my stock SS 9.5 rear wheels and they can spin at under 60 with just a few bolt ons even. Also had some 305/30 SC3 tires on 11s and those spun at low speed surprisingly easily despite their 220TW rating. I did have a centrifugal blower in the past, and I did not bother racing that config without some drag radials. MT drag radials worked decent, and I ran in the 10s with them. But they are not so great for street driving, perhaps those new Nitto NT555RII might be a better compromise for street use while still having some acceleration grip due to their soft rubber (100TW)? They are a 'drag radial' but not as radical as some others are. If you are looking for a combination of both acceleration grip and cornering grip, then I hear that the Toyo R888R (road racing tire) works pretty well, though it's apparently got a lot of road noise to contend with.

I am curious, what would be more noticeable - swapping to high quality summer compound on the LT1 stock wheels (245/40) or moving from high quality summer compound on 245 to same tire on the 275/285 range?

[Msquared]

Originally Posted by Crushin_LT1

I am curious, what would be more noticeable - swapping to high quality summer compound on the LT1 stock wheels (245/40) or moving from high quality summer compound on 245 to same tire on the 275/285 range?

Probably changing to "high quality summer compound" on stock wheels from the OE all-seasons. It depends on exactly what you mean by that descriptor, but even a Michelin PS4 or Continental EC Sport will be a massive improvement in grip over the stock all-seasons. If you go with a Falken RT660 or Nitto R888R, there will be lots of compromises (mileage wear and road noise, to name a couple) but you will be amazed how much better it will hook up.

Going with wider tires (increasing the contact patch size) of the same compound will help grip, but not as much. The reason is found in the basic formula for friction force: Fn x u, where Fn is is the normal force (load) and u is the coefficient of friction. if the coefficient remains constant, then friction force increase with the load normalize to contact patch area (PSI), and it doesn't matter how wide the contact patch is: the friction force (grip) will be the same. However, with tires, the coefficient of friction actually drops as load increases, which is the only reason that wider tires (or taller - anything that increases the area of the contact patch) improves grip. It's also the only reason that weight transfer during braking or cornering is a bad thing. Anyway, the thing is that the coefficient of friction rises a little as load decreases, but not as much as improving the rubber compound will increase the u.

[Crushin_LT1]

Originally Posted by Msquared

Probably changing to "high quality summer compound" on stock wheels from the OE all-seasons. It depends on exactly what you mean by that descriptor, but even a Michelin PS4 or Continental EC Sport will be a massive improvement in grip over the stock all-seasons. If you go with a Falken RT660 or Nitto R888R, there will be lots of compromises (mileage wear and road noise, to name a couple) but you will be amazed how much better it will hook up.

That is kind of what I figured, I meant something like Conti ECS, MPS4S, Firehawk Indy 500, Bridgestone PP S-04 type tires, General G-Max.

Originally Posted by Msquared

Going with wider tires (increasing the contact patch size) of the same compound will help grip, but not as much. The reason is found in the basic formula for friction force: Fn x u, where Fn is is the normal force (load) and u is the coefficient of friction. if the coefficient remains constant, then friction force increase with the load normalize to contact patch area (PSI), and it doesn't matter how wide the contact patch is: the friction force (grip) will be the same. However, with tires, the coefficient of friction actually drops as load increases, which is the only reason that wider tires (or taller - anything that increases the area of the contact patch) improves grip. It's also the only reason that weight transfer during braking or cornering is a bad thing. Anyway, the thing is that the coefficient of friction rises a little as load decreases, but not as much as improving the rubber compound will increase the u.

Long-term I would like to eventually go wider wheels, but the current all-seasons are pretty brutal for grip with 450hp. When I asked at the dealer about going wider wheels - they actually told me going more than 275 or 285 might increase the chance of hydroplaning in a daily driver.

[arpad_m]

Originally Posted by Crushin_LT1

Long-term I would like to eventually go wider wheels, but the current all-seasons are pretty brutal for grip with 450hp. When I asked at the dealer about going wider wheels - they actually told me going more than 275 or 285 might increase the chance of hydroplaning in a daily driver.

While technically this may be correct, it most heavily depends on your tire of choice and its water evacuation ability. Hydroplaning in a downpour is a given with 305 or 315mm wide R888Rs, but it probably won't ever happen with the PS4S (then again, you'll sacrifice some dry straight line traction—tradeoffs everywhere )

[Crushin_LT1]

Originally Posted by arpad_m

While technically this may be correct, it most heavily depends on your tire of choice and its water evacuation ability. Hydroplaning in a downpour is a given with 305 or 315mm wide R888Rs, but it probably won't ever happen with the PS4S (then again, you'll sacrifice some dry straight line traction—tradeoffs everywhere )

Tradeoffs are always fun, it does downpour a lot in Florida. I wasn't looking to go any bigger than 285s, it would be unnecessary for me - I don't track the car, just some spirited driving.

The stock all seasons are brutal in the rain though, tirerack has them rated well for wet, but that doesn't indicate actual performance down here in the real world.

[Msquared]

I agree with everything arpad wrote. I have been daily-driving my SS 1LE on base model 18x8.5 with 245/50/18 Toyo Versados, so I understand what you mean about bad grip (even the OE all-seasons on the LT1 cars are probably a lot better than these POS Toyos!). I think Florida is the perfect environment for the PS4 or ECS. They are good enough in the rain that many autocrossers use them as rain tires, and they have great grip down to freezing. They aren't good for ice and snow, but...Florida. For sizes, any easy upgrade would be to SS wheel and tire sizes. There's not really any reason you couldn't go to SS 1LE wheel and tire sizes, except for cost. But the PS4 or ECS in SS Camaro sizes will be a massive improvement in grip for you.

[CaptainChad]

Yo guys, I'm glad my thread gained some traction and we're having a conversation. I'm going to take everything that everyone has said into consideration, including what the user said above about what my goals are for the car.


I've read through all the comments but I'm going to re-read through everything you guys said and do some research to truly understand where to go from here, but I'm glad you guys are sharing your knowledge.

[Ponyeatr16ss]

I have two Camaro’s and personally I’ve built both in reverse order. Suspension equals traction I don’t care what wheels and tires you throw at a car. The stock suspension is just ok. Brakes. Then tranny then engine.

[Shawnqa800720]

Originally Posted by Ponyeatr16ss

I have two Camaro’s and personally I’ve built both in reverse order. Suspension equals traction I don’t care what wheels and tires you throw at a car. The stock suspension is just ok. Brakes. Then tranny then engine.

Suspension equals feel, precision, and stability, not traction. Tires equal traction. The suspension can help the tires maintain traction or thwart it (body roll, etc.), but the tires do the sticking since they are the only part in contact with the pavement. They do all work together though, and they work in concert. Understanding what you want the car to do is the first step.

[Ponyeatr16ss]

Originally Posted by Shawnqa800720

Suspension equals feel, precision, and stability, not traction. Tires equal traction. The suspension can help the tires maintain traction or thwart it (body roll, etc.), but the tires do the sticking since they are the only part in contact with the pavement. They do all work together though, and they work in concert. Understanding what you want the car to do is the first step.

If you’re building a car to go fast, stick to the ground, and support power. You’re not building it for “feel”. 🤣 you can have the stickiest tires in the world, but if you don’t have a suspension to support it they’re worthless. My one seater is far from being comfortable to “drive” for feel. But it goes really fast in a straight line and not one spin off the line since it was bone stock.