Anyone know whats the tallest widest tire I can get on the front and on the rear if i got 18x8 wheels and stock suspension? car is a 94 z28

 

I can understand why you want a "widest" tire.... 275 or 285 is generally the max, but there are people running 315's if you don't mind them sticking outside the fender a bit. But why do you want the "tallest" tire? You should make every effort to match the stock tire diameter.

And, you are limiting yourself a bit with the 8" wheel width. Most people will opt for a 9.0 or 9.5" width in the front, just so they can use a wider tire. With the 8's you are limited to a 245/40-18, which is no wider than a stock wheel/tire. And it matches the stock 25.65" overall diameter of the stock wheel/tire combo, at least if your car came with the Z-rated tires.

As an example for a taller tire, you would be looking at a 245/50-18, and that would make your car look sort of like an SUV, with a diameter 2" larger than stock.

 

since im curious about this anyway and am tryin to get a good set of tires for the 17x8.5/18x9.5 combo z06's im about to get.. whats the widest tire that works well on a 9.5in wheel? and how bad would a 275/40/18 on back and a 245/40/17 on back be compared to stock tire diameter? in other words how much higher would the back be than the front..

 

Well the height I dont care to much about, I just need more rubber to the pavement.
I got 235/40/18 atm and they suck for rear tires, not to mention they are actually smaller than the rim as far as width so that makes them look silly and perform crappy
I was misslead on the sale of these rims and did not want to pay to ship them back so I'm just trying to make them work as best as I can.

 

Can I assume you mean 245/40-17 on the "front"?

Bad combo.... one is an inch smaller than stock and the other is an inch larger than stock. The back tire is 2" larger than the front, the back of your car would sit 1" higher than the front. Speedo would be off.

A 245/40-17 is too small a diameter. It is only 24.7". You want to match the stock tire diameter, which is 25.6" (assuming your car came with the optional Z-rated 245/50-16 tires). You would want a 245/45-17 to match the stock diameter.

In the back, the 275/40-18 would be a 26.7" diameter. You need to use either a 275/35-18 (25.6") of a 285/35-18 (25.85").

Unless of course you are intentionally trying for a "rake".

 

How can I tell what width will safely stay on the 8"rim

 

I pretty much answered that:
To verify that info, go to Tire Rack. Click on "search by size". Put in that size, and you will get a list of more than 60 tires available in that size. For any tire you are interested in, click on the "specs" button. It will show you the dimensions of the tire, and the manufacturer's recommended wheel width range. Check several tires... not all manufacturers recommend the same rim width for the same size tire.

For the 245/40-18, the typical recommended rim width is 8.0" to 9.5". With your 8.0's, you are at the very low range of the allowable rim width. A 255 is going to want at least an 8.5" rim, a 265 will need a 9.0" rim.

You can put a tire on a narrower rim than the manufacturer recommends, but you run the risk of deforming the contact patch, increasing flexing to the extent where heat starts to build up, and tread and carcass life is shortened. And, putting too wide a tire on too narrow a rim will end up looking exactly like what it is... with the sidewall bulging out incorrectly from the rim.

 

Thanks for the info man

I never noticed that button and thats exactly what I was wanting