dllhg

First of all my car is a Supervette wide body. It is 3 inches wider in front and back. Rear rims are 13 inch the fronts I believe are 10 or 10.5 inch. I have LG adjustable coilovers.
There are just terrible selections for 345 25 20 that is presently on this car. I really want PSS or sport cup 2s but they only come in 345 30 20. Considering going Sport Cup 2 in rear
and Super Sport up front. $200 less per tire on the fronts. Rears only $40 difference for some reason and I need as much traction as I can get. If I can get 5-6K miles out of rears I can live with that.

Check out picture below for how the 345 25 20s and 295 25 20 sit. The 345s are actually a little narrow on that rim. The 295 25 fronts in there now just barely touch at full turn on the inside. Was thinking 285s would help a bit with that.


Rear tires would be 4.9% larger diameter and fronts would be 3.5% larger. So it looks pretty darn close front to back. Other than speedometer being off would I be okay with that difference between the two?
Looks like they would be about 1.3 inches larger in diameter. Would be .65 inches less gap than I have now for the rears and a tad less for the fronts.


Here are exact specs and differences.

Rear tire 345/25R20 vs 345/30R20

Diameter
26.8" VS 28.1" +4.9%

Sidewall
3.4" vs 4.1" +20.6%

Circum.
84.1" vs 88.4" +4.9%

Revs/Mile
753 vs 717 -4.9%



Front tires 295/25R20 vs 285/30R20

Diameter
25.8" vs 26.7" +3.5%

Width
11.6" vs 11.2" -3.4%

Sidewall
2.9" vs 3.4" +17.2%

Circum.
81" vs 83.9" +3.5%

Revs/Mile
782 vs 755 -3.5%

dllhg

I need some damn tires ! Cant stand these Nitto Invos. They suck off the line and dont inspire confidence in corners either.

long_tall_texan

See the image below for a comparison. Top row is rear OEM size vs your current size vs. the size you are wanting to go to. Bottom row is same for fronts.



The front to rear ratio should be OK, and not give you any traction control system error messages. My only concern is that you would be going an inch taller tire up front, and almost an inch and a half on the rear. You may need to adjust your ride height after the new sizes are installed if you experience any tire rubbing on fender liners over the bumps.

dllhg

Thanks.

While it will be 1.3 inches taller tire in the back it will actually only fill the gap 50% of that which is .65 inches. The front will be about .5 inches.
Still may rub not sure. I dont know if the ride height can be adjusted higher than it is now or now honestly.

My tires are getting smooth patches. No cords showing yet but they really stink.
So tempted to get the Sport Cup 2 for the rear but I will only be able to enjoy them for maybe 3 more months and then I might have to put super sports on. Wont see rain but will see cooler temps. Coldest it gets here during the daytime is low 50s but thats enough for a lot of tires to really lose grip.

I may just get Super sports all around. At current power level I am sure that will be plenty. When I go up 100-150 more WHP I am not sure. I just remember in my e55 how much faster and consistent my car was when I got some R compound Ra1s in the rear.
That being said the biggest improvement was when I went from Hankook V12s to the Super Sports. Dropped a full second off my 0-60 times via V-box. The RA1s gave me a few more tenths and required less skill to launch too.

long_tall_texan

Probably won't know if you need to raise it by looking at it. If you start rubbing rear fenders in liner you will know it. You'll hear it when you hit a dip or bump on the highway. Very easy to raise ride height if needed using stock bolts. There's a how-to on here. Just search and you will find it if needed. Just looking at your vette in the pics, you should be able to raise it a whole inch if you needed. So the size you are wanting to get should be safe for you.

dllhg

Thanks. I feel better now about ordering these tires. Rears are nearly $600 each. Will need to find out how to re calibrate speedometer in HP tuner. I don't want it to be off 5%.

dllhg

Well bummer, they rubbed pretty bad on bumps at hwy speeds. I raised the car enough to clear but now it looks like an SUV to me...... Adding almost an inch and a half to diameter doesnt look right with car raised. Looked great when I put the tires on with decreased gap but it rubs too much. Tires raised the car .7 inches and we raised suspension another 1.3 inches. 2 inches higher and it just looks too high off the ground. Front tires also hit the front of wheel well at full turn. Not the top on bumps but the front.

I only put about 50 miles on them. I am going to see If Americas Tire CO will be willing to exchange them with another tire. They state on their website that if you are unhappy for any reason they will do whatever it takes to make you happy. Will see. I can get Super Sport ZP in a 335 25 20. Little concerned they will be too narrow on the 13 inch rim. I am guessing they wont be any narrower than the 345 Nitto Invos ....

dllhg

Crap the 335 are 4/10th of an inch narrower and I'm running a 13 inch rim. Not sure that will fill in the rim enough. The 345s look like they fit perfect. Looking at specs the Invoes I had on there were about 2/10th Narrower than these 345 PSS and they fit fine. You can see those tires in picture above. The front tires in picture above are 295 25 and looking at the 285 PSS they seem to fit flush with rim protector sticking out slightly beyond rim. Hate to try and exchange them and have the rim stick out beyond the tire which would look odd. PSS definitely run larger than the Nittos Invoes in the same sizes. Only other option I see is P-zeros come in 345 25 20. Freaking $730 per rear tire .....

Forsellb

First, what rim do you have that's 13 inches wide? Secondly, I'm surprised they rub. I have Toyo R888 285 18s in front and 345 19s in the rear and I don't rub. I have plenty of room, too.

long_tall_texan

Same here. I'm running 285/345 combo on stock width/offset 18/19 wheels and I don't rub lowered all the way on took bolts. Sounds like the wider wheel may be combined with an offset that is not Vette friendly.

dllhg

Check out images on first post to see what the Invo 345 25 20 and 295 25 20 look like. Rims are Niche rims. Dude paid over 7K for these rims. They do have a different offset since each fenders on the Supervette is 1.5 inches wider or 3 inches wider front and back total.

They didnt rub with that sized Nitto Invo but these new tires are .68 inches taller sidewall. Im think I am going to get the 335 25 20 PSS ZP. Everyone seems to say that the Invos run about 2 sizes narrow. Just hope the tire dealer takes them back. Less than 10 miles on them.

nashvegas

Selling my 345/30r/20's, Michellin Pilot Super Sport, non-run flats. I had a little bit of rubbing on the rear driver side, going with 325's. Paid $500/each, sell the set for $650 delivered. Less than 75 miles on the tires.

dllhg

I went with the 325s. They are in fact just as wide as the 345 Invos but are 100% better tire all around. No comparison. The 345 didnt look right at all on my car with these rims. Plus they rubbed a lot. Luckily they just swapped them out for no fee.

FYI you might try that if you bought yours locally. Michelin is pretty good about exchanges. Mine had a couple hundred miles on them.

Send it scott

I hate the invos also. They are rock hard and don't perform good at all. I went with 345 30 20 ps4's and couldn't be happier.