[jeffyhopper]

The post was originally put into the Convertible subforum, but not too many people go there……That’s why I moved here.
I used the forum search function looking for the rim/tire upgrade options. However, there is not much info from the perspective of a V8 convertible owner. Thus, I think this is a good place to ask for your opinions and thank you for your input ahead of time!

(1) LT1 (V8) convertible comes with all season 245mm tires on 4 corners, I am wondering how bad this would be for some back road/curvy fun in California? No plans for track use, as a convertible is not really built toward that.

(2) Assuming I will take the route of upgrading the grip of the LT1 vert for better assurance while having fun on curvy roads, will swapping for grippy performance summer tires at 245mm width at all 4 corners a good enough option? In other words, since a vert is more of for the backroad fun and cruising under good weather, will it be an over kill if I go for the SS (245F/275R) or even SS 1LE(285F/305R) wide and staggered tire set-up? I have to admit this is more of a question about cost/effectiveness, and 245mm summer performance on 4 corners sounds like the most bang for the buck.

[Gen6cyl]

I got 245-40-20 general g max summer tires at discount tire. Put on about $950 .Great tire.

[tlr3715]

You should see my thread about tire width and E-throttle rant. Very relevant to this topic. My opinion 245 width is no where near enough tire for 455 HP. Go wide and enjoy your engine.

[dpevans]

If you don't want to purchase new rims I would put Eagle F1 SC3 255/45/20 square. It will only throw your speedo off by 1/2 mph at 50 and give all the traction you want.

[jeffyhopper]

Originally Posted by tlr3715

You should see my thread about tire width and E-throttle rant. Very relevant to this topic. My opinion 245 width is no where near enough tire for 455 HP. Go wide and enjoy your engine.

Hello, your observation of a decreasing ratio between tire width and engine maximum horsepower from late 1990s to nowadays are valid. But it is not sufficient to justify your point.
A better way to describe whether car manufacturers have mistakenly undersized the tire on the ever more powerful sports cars would be the ratio: (maximum horsepower/maximum friction force can give by tires). With just the ratio you proposed (tire width/horsepower), it is insufficient to evaluate whether the tire width is capable for a given horsepower, because apparently modern tires are more grippy (i.e. provide higher friction force with the same area under the same downward pressure) thanks to the advancement in chemistry. Not to mention the stability control and other performance technologies have improved a lot on modern sports cars.
For your reference, gen6 Camaro ZL1 1LE (lap time: 2:45.0), Camaro SS 1LE (2:54.8) are faster on the same track with ever more impressive lap time comparing to those sports cars in the 1990s and early 2000s.To clarify, the lap times are nicely complied by Car and Driver: https://www.caranddriver.com/feature...storical-data/. Yet, you will find Camaro ZL1 1LE and Camaro SS1LE did poorly for the ratio of tire width/horsepower, ZL1 1LE is about 0.5 (325mm/650hp) and Camaro SS 1LE is 0.68 (305mm/450hp). Would you say Chevy “underwheeled” these 2 cars because they are so low on the width/horsepower ratio? If ZL1 1LE is more slippery than SS 1LE due to a lower ratio of tire width/horsepower, how did ZL1 1LE finish the track quicker than SS1LE?
Another piece of data would be, the lap time for the gen5 Camaro SS 1LE (2:54.8) is almost as good as 2009 Chevrolet Corvette ZR1(2:51.8). I can say 2009 Chevrolet Corvette ZR1(over 600hp) has a wider tire (335mm) and way more horsepower than Camaro SS1LE but failed to do proportionally better.
With these data above, maybe I can say a lower width/horsepower ratio marks the advancement in modern day sports car technology. There will always be a trade off between weight, rolling friction, maximum grip and faster lap time.

[Gen6cyl]

You could get forge one ff10 wheels that weigh 20 lbs 19-9 , 25mm offset and get 255- 40- 19 general g max tires 25 lbs. You would be 15 lbs lighter at each corner. That would be almost $4k from tire rack.

[Msquared]

Wider is always better on dry pavement, but you can probably get an even greater increase in grip from changing tires and compounds within the same than wider of the same kind of tire. Of course, if you get wider wheels and tires, you should get better tires too! Either way, in your climate I would recommend Michelin Pilot Sport 4S or Continental ExtremeContact Sport tires. They will be grippier in the dry and they are the two best rain tires you can buy, period.

[LT1gen6]

Go wide wide

[donniedarko]

I had a 16’ SS wit staggered set up and current 21’ LT1.
I have 0 tramlining on the fwy now, but in SS was horrible.
I likened to staggered vs square set up.
As for lack of tractability, at speed even spirited cyn driving in Malibu no issue even in run flats. I’ll say hook up is pretty poor. But honestly Im not dragging or racing car, but I don’t mind blowing out the tires when appropriately inappropriate.

I do anticipate going staggered if I get new wheels.

[LT1gen6]

Phat and skinny, all in one.

https://www.caranddriver.com/feature...res-explainer/

[Gunkk]

I have 235/50R18s MPS4S's on my 4200 lb Genesis v8 380hp luxo barge daily driver. Tires grip just fine. The car is chassis limited not tire limited.

I don't recommend a staggered setup unless you're going to do a lot of straight line launching, and even then you have to keep the diameters close to avoid stabilitrack issues. IMO staggered not necessary for canyon carving, and you'll lose most if not all of your treadwear warranty if that matters.

Even with the superior chassis and extra weight, a LT1 vert Camaro at 3800ish lbs should do just fine in canyons with 245s if they're the right tire. I would have no concerns putting MPS4S's on a LT1 vert. Did an BMW autocross event and they ran tires smaller than 245 on their cars. I plan to put a set of MPS4S on my ZL1 vert here soon.

[LT4Greg]

Jeffy, I would look in the members classified section for some take off SS wheels and run the stock size tires. The 275s in the rear will make a difference as compared to the 245s you have now but definitely go with Michelin or Continental tires for the better ride and handling since they aren’t run flat tires.

[Crushin_LT1]

I went to larger wheels (10in w/285 summers). Huge difference.

[DorsoDuroJohn]

285/305 GO, you'll never regret it. The 245's are just loosy goosy all day long with that motor. I was spinning everywhere on the stock wheels and tires. So i guess you could say it's all about throttle control, but i can assure you that the 285/305 setup on an LT1 is far superior.