I've noticed that the availability of tires goes up a significant bit if you look at tires with a lower aspect ratio. Using factory widths on factory thin-spokes with aspect ratios of 35 and 40 instead of 40 and 45 opens up some tempting possibilities. I have no doubt that these tires will fit and work, but I've been unable to find much information on what the actual effect is on a C5. Does this make the ride significantly harsher? Do the tires look too small and the wheel gap too big? Is anyone using Riken Raptors in these sizes? I have liked these tires on other cars and I imagine I'd like them on the C5.

I read through a plethora of tire size threads and found some info but considering the vast collection of various tire size threads I was unable to find one that really settled my curiosity in this matter. Thanks in advance for any helpful responses.

 

Just based on some general tire knowledge, going to a shorter sidewall (smaller aspect ratio number) will increase the tire to wheel well gap UNLESS you go with a tire that's wide enough to make up for the overall height difference. For example the sidewall would be taller on a 305/35 than it would be on a 275/35 because the aspect ratio is the percent of tire width...So if you want to drop the aspect ratio on the rear tires from 40 to 35, you'd probably have to go to at least a 295 width tire to make up the height, but I don't know if a tire that wide will fit on a stock rim...

 

I realize that the diameter would be smaller. I'm asking if the negative effects of the smaller diameter are significantly noticeable or if the difference is not such a big change from the perspective of those with experience with tires of lower aspect ratios than the stock sizes.

 

That I couldn't tell you...

 

Rough numbers... each drop in aspect ratio is about equivalent to an inch in diameter or 3 width jumps.
Example:
265 40 17 = 25.35"
265 35 18 = 25.30"
295 35 17 = 25.13"
So going down one aspect ratio will drop your overall diameters about an inch. This will affect:
Appearance; less wheel well filling, will look off IMO
Final drive ratio; will be raised a bit, faster off the line, reduced top end speed, speedometer will be off (around 4% off)
Food for thought.

 

Also the lower profile you go, the crappier the ride quality. Sidewalls become stiffer to make up for being shorter. I put lo pro's on my Camaro. Looks great, but ride quality took a hit.

 

Thanks for the responses. I do understand the theoretical difference. I'm really looking for real world feedback from people that have tried these sizes on a c5.

 

The lower the aspect ratio the better the car will handle and the firmer the ride. With the stock C5 I went with the front tire from 245/45x17 to 255/40x17. However it was from runflat to non-runflat tires and I did not notice any difference in ride quality. Today I am running 275/35x18 front and 305/30x19 rear and do not feel any difference in ride quality at 30 psi. Handling is considerably better with the larger tires but with larger wheels and width, I have close to the same amount of rubber between ground and wheel in the front tires.

 

what happens if you go +1 on the width?

You could pick a smaller aspect in a wider than stock size to keep diameter closer to stock.

Just a thought, but I don't know what tire sizes you're shopping for specifically.

I've used this free tool for a long time:

https://www.miata.net/garage/tirecalcold.html

 

I'm running C6 Z06 wheels and the ride is not harsh.

 

Thanks for the responses. It's sounding like the difference isn't too bad in practice.

 

Standard C6 tires have good availability.

 

That's good to know. I might see if I can find a set of c6 wheels then for street tires.

 

The most noticeable situation that would potentially occur with altering aspect ratio from OEM would be traction control, active handling, and selective/mag ride, as a combination of those functioning. Those devices on your car rely on not only how you car is handling but also the ability of your tires to perform properly. If all of a sudden your tire has a more difficult time adjusting to grip to say carrying a stiffer side-wall (I'm throwing a hypothetical out there...) then you may see traction control or similar activate earlier than it would normally need to.

Other than that I'd presume it'll come down to aesthetics.

You'll likely read stories of people saying "well, OEM recommends this blah blah blah size." Indeed that is true and obviously engineers work to determine the ideal size tire to place onto cars (remember, they're the only safety feature that's actually touching the road). However Corvettes do not "use" tires in the same manner as most common vehicles. You don't follow the same rotation schedule for example (most tires can't be rotated at all) and thus because of this proper maintenance in the form of maintaining air pressure and alignment becomes key. At best a tire on a Corvette probably sees roughly 50%-70% mileage life compared to had it been equipped on a normal road car due to these situations.

 

In terms of ride harshness it depends on the construction of the tire. My experience on another car in 30 aspect ratio there was significant difference in feel between michelin and pirelli. Pirellis felt softer. For what its worth.

 

IMO all the tires that are worth looking at for use on a stock C5 are already available in stock C5 sizes with the exception of the Michelin PS4S, but that will come sooner or later.

 

I've been researching tires and came across the website below. It's a handy tool to see a different size compares to the factory.

tiresize.com/comparison/