When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The 93 Convertible I have has 19" wheels in the back with 295/50/19 (I think , sorry) ,,, same size tire as stock anyway but on the 19" wheel. The car seems to be a crazy monster when the traction assist is turned off, squirrely doesn't even begin to describe it. My question is : Are the 19" wheels screwing up the dynamic of the suspension and traction/abs systems ?
Most stock '93's have a 285/40/17 rear tire that is about 26.0" in height (outside diameter).
The 295/50/19 tire is about 30.6" in height.
That is way off. When your speedometer reads 60 mph you would actually be going 70.7 mph.
The traction control is to sense when the rear tires are spinning and turning faster than the fronts. In this case they would be turning slower so probably would not cause traction control problems. When the system is turned off, it would ignore any speed differences between front and rear.
I am not sure on the ABS. It would only function while braking, but with that much difference in tire heights (and rotation speeds), it may be confused and act funny.
In short, those tires are way off in size. but like Paur Workman said, something isn't right and more info is needed.
I'm guessing they are really 295/30/19, which are 26" tall. Those need to be on wheels that are at least 10" wide. Assuming those two conditions are true, then tire size is not the cause of the handling problems.
You are not blowing those tall of tires off with a stock car.
As pointed out above, either you posted the wrong size tire, or you have a heavily modified car.
Going up in wheel size inches changes your gear ratio. Like if you have a 3.07 gear and put on a bigger wheel and taller tire combo you just dropped your ratio down to a 2.73 or whatever the math is per inch and ratio you have. So it would have a much harder time to spin tires. The speedo will be off but you would get a little better MPG.
Obvious place to start is what and how old the tires are. Of they're something like a nitro invo, and also pretty old, yeah I could see 300hp blowing them apart. Tires get harder as they age, and a cheaper set of tires may start off pretty hard.
sorry for the confusion and very much appreciate the replies. The car has 285/40/19 on it now : Goodyear F1 ties in fair shape (I don't know how old they are but the car was very well cared for by the previous owner). So, a new set of tires would change the behavior of the car for sure.
What I am pondering is if the two inch increase could be messing with the TC , ABS and such to the point it makes the car want to come around when getting on it from a start while driving in anything but a straight line ?
The TC does a great job and the car is very stable with Traction Assist on. The issue described above in when I shut it off.
Thanks for the help from a Corvette newbie. Very enjoyable car and not unhappy just looking the know more.
The car has 285/40/19 on it now : Goodyear F1 ties in fair shape (I don't know how old they are but the car was very well cared for by the previous owner). So, a new set of tires would change the behavior of the car for sure.
What I am pondering is if the two inch increase could be messing with the TC , ABS and such to the point it makes the car want to come around when getting on it from a start while driving in anything but a straight line ?
The TC does a great job and the car is very stable with Traction Assist on. The issue described above in when I shut it off.
Thanks for the help from a Corvette newbie. Very enjoyable car and not unhappy just looking the know more.
Okay, that's a 28" tire height, which is at least 2" taller than stock. It is not going to mess with the TC and ABS electronics in a 93 C4. But it does significantly raise the roll center and CG in the rear. This has several effects on handling balance, all of them in the direction of losing rear cornering grip. First, the higher static CG increases lateral weight transfer across the rear tires, reducing grip. Second, the higher rear roll center (or, more properly the higher anti-roll geometry) introduces a jacking effect to the rear suspension when cornering. This jacking effect raises the CG even higher during cornering, and it also creates a "geometric spring" of sorts that creates more roll resistance. Both of these factors also reduce rear grip during cornering.
So the short answer is: yes, the too-tall tires will cause your car to be more prone to lose rear grip in cornering. This would be the case on any car, regardless of whether it has TC or ABS. It's a result of basic suspension geometry, not electronics.
The dramatic difference in diameter in a C4 can set up unwanted situations. The EBTCM is seeing the difference in wheel speeds which could result in unwanted activation. The C5 + are calibrated for smaller diameter front tires.
The 285/40/19 is a pretty tall tire for the rear end, combined with the already taller rim - A 30 or 35 series tire would be the better tire for a decent ride height but that shouldn't be the cause.
I suspect bad rear tires, they may look fine thread wise but might be hard as a rock so they would break loose coming around corners or make you feel like you have a ton of power since you're able to break 'em free at will so to speak. Some of these rarely driven or lower mileage cars that I've seen seem to have had the tires go bad, not due to low thread wear but due to old age/dry rot. When I bought my 94 back in 2017 it had somewhere around 44k miles, the Goodyear tires looked great (thread) but I had to quickly replace them as they were dry-rotting/hard from sitting and aging as someone's garage queen.
Post a picture of the tires up close and we can get the week/year the tires were produced OR here is how to check the code:
Thank you all for the reply and help !
So now I ask about steering column and cowl shake in the convertible. Is there anything that can be done to lessen it ?
larger rear wheels cause problems ?
