C5 Corvette Square Setup Wheels/Tires + Federal 595RS-RR tires in 275/35R18 & 305/30R18

In my quest for improved performance and handling on a budget, one thing I heard a lot of people mention was that some people would go with a "square" setup for wheels/tires. A square setup is equal on all 4 corners, so the same size wheels and tires, which for those of you who don't know, differs from the OEM staggered situation of a larger rear wheel/tire combo than front. This works as a cheap alternative as OEM base rear wheels will fit on the front and let you run a 275 width tire all around, and the wheels themselves are quite plentiful. I found a pair for $99ea shipped, and I then had them powder coated for an additional $99 each. $200 a wheel is pretty hard to beat I would say, especially since you only need two to make this upgrade.

The most important pro of this upgrade are that you get notably improved traction. You can also accomplish this swap for pretty cheap by comparison to other upgrades, as I mentioned above. 

A frequently mentioned con however, is that your traction control supposedly is compromised by such a setup.

I went ahead, installed this setup with some of the Federal 595RS-RR tires, and here's some information on how it all went.

Undiscssued things you will need to handle as part of the swap/install/whatever

One thing people don't mention is that if you go with wider tires on larger wheels up front, you're going to gain some height up front. Also this frequently means a reduction in height in the rear as well as you generally will have a 35 profile front and rear, and not the 40 profile rear typically found. This means the front will be higher than stock, and the rear will droper lower than stock.

I personally lowered the stock front spring adjusters as low as they could go along with the rear springs. This in the end acheived a balanced configuration with only a 4mm drop on all 4 corners, which is roughly an 1/8".

Another minor headache, is if the tire installer mixes up the tire pressure sensors, you will need to reset the tire pressure monitors. Turns out, this is pretty easy with a magnet and accessing the learning mode in your DIC. Here are the steps:

1. Turn the ignition switch to the ON position. (Engine should be off.)
2. Press the RESET button on the Driver Information Center (DIC) to clear any Instrument Panel Cluster (IPC) warning messages.
3. Press and release the OPTIONS button on the DIC to cycle through the display options until the IPC display becomes blank.
4. Press and hold the RESET button until the “FOB TRAINING” message appears.
5. Press the OPTIONS button once and a “TIRE TRAINING” message will appear.
6. Press the RESET button once and a “LEARN L FRONT TIRE” message will appear. This message signals the beginning of the programming sequence.
7. Hold the Tire Pressure Monitoring System (TPMS) Programming Tool over the valve stem of the left front wheel (NOTE: Just use a BIG magnet here). When the horn beeps once, programming is complete for the left front wheel ONLY. NOTE: You may have to move the tool around the valve stem to hit the right spot.
8. After the horn beep, proceed to program the remaining three sensors (Front right, back right, back left). You MUST program the sensors in the order directed by the IPC messages.
9. The order of programming is fairly simple to follow. First, start with the (1) LEFT FRONT WHEEL. Wait for the horn beep. Then, move to the (2) RIGHT FRONT WHEEL. Wait for the horn beep. After, move to the (3) RIGHT REAR WHEEL. Wait for the horn beep. Finally, move to the (4) LEFT REAR WHEEL. Wait for the horn beep.
10. The programming/reset process has successfully been completed at this point.

Does this actually mess up traction control?

A thing people frequently mentioned is that the traction control expects there to be a difference between the front and rear diameters, and with the setup being square it will cause the traction control system to trigger earlier than before. I took my setup out on a VERY spirited ride after install, and I have to say, I did not find this to be the case. While I did notice traction control kicking in a few times, It was hardly an unbearable, and I was driving in notable excess of what your average driver should have been doing in those situations. Overall, I have to say the traction control concerns are very much overstated.

How did this setup work aesthetically speaking?

So I personally am not into this for aesthetics as much as I am function, but I can't say I want my car to look like crud either. Overall, I'd say this setup and configuration works pretty well, but not perfect. The front wheel well (picture below) is actually an awesome fit and look as far as being flush and filling out the wheel well. I'd definitely give this an A to A+ rating.

The rear however, suffers the same problems as the base model ride height and tire size, albiet slightly improved. The rear wheel well is pretty huge, and it just isn't filled up very well by the rear wheel, but is an improvement over stock with the rear wheel lowered the 1/8". I would overall give this change a B rating.

Overall, the look is a bit imbalanced from front to rear. If it's looks youare after, this is NOT what you want, but an improvement over OEM still.

I think the ideal situation as far as looks goes, while also incidentally benefiting traction (especially if you've got power adders on here) would be to go with an aftermarket wheel size/offset that matches the C5 base model rear wheel (as I have used here) and then find a rear tire that is 315/30/19. The increased width and likely diameter tire/wheel combination in the rear will fill out that rear wheel well better. The increased size rear wheel will however come at a slightl additional cost as you will need longer lowering springs for the reat to restore a balanced ride height. An added bonus of this configuration is that any additional considerations for the traction system handling offset wheel size will be alleviated as you will yet again have staggered wheel sizes.

Acheiving the larger wheel/tire sizes though also incurrs notable additional cost as you will need 4x aftermarket wheels. This will run you at least $1000 for wheels alone, while my setup ran $400 for just 2x wheels. My cost does not include any considerations for offloading the front wheels, although demand for the OEM base model front wheels is undetermined at this point.

What are your initial impressions of the Federal 595RS-RR

I picked up the federal 595RS-RR tires as they are VERY affordably priced tires in this tire size. I heard a few details that specifically gave me a lot of interest, with the most important word being "predictable". I like a tire that lets you know it's going to break loose, and then as it breaks loose does so in a progressive fashion instead of an expoential "traction suddenly is nowhere to be had" fashion.  While I perhaps am giving up some grip for this and perhaps leaving a second or two on my track times... I'm just here to shred so what do I care?!?

Allow me to just say, as "loud" as these tires are supposedly, I found it quite bearable and not as noticable as advertised. While other tires barely have any noise until you're squealing them around a turn, these do have a light background sound to them. They are nothing compared to even a modest exhaust system volume however. I personally took my spirited drive out with the windows down and no radio and forgot all about the noise on them personally. For me, it just wasn't a thing. Now if you're doing 80+ on the highway and turning 1k rpm with the windows up trying to listen to faint classical music, sure it may bother you... but I'm in a corvette and it's setup to shred, that ain't happening!

The tires themselves in this configuration on the C5 Corvette were great. Steering wheel effort did increase, and they did track bumps and oddities in the street more. That said, feel was significantly improved and traction was phenomenal.

How the 275/35R18 Federal 595RS-RR tires handled at the track.

At the track, these tires were great! I purchased these around my fifth or so track day, and the improvement in traction was notable. I however was struggling with some suspension configuration issues, but the tires themselves did their job pretty good, and most importantly they provided exceptional audible feedback as they began to slide.

I did run into some overheating problems later with the larger 305/35R18 federal tires as I began to push my lap paces substantially, and I surely would have had the same problem with these 275s as well. The tires would get pretty hot when pushed hard, and start to become "greasy" if you will and be more prone to slide around. Still, these tires would let you know long before hand via screeching that they were getting too hot, and would definitely let you know they were hot when they were overheated.

I would also like to point out that the druability of these tires is pretty substantial. I put a large amount of track days on all of my Federal 595RS-RRs and they lasted a surprisingly large amount of time compared to other 200tw tires. If the treadwear rating were actually legitimate, these might qualify as 250~ treadwear tires I'd esuspect.