ok guys this is prolly stupid and usually I just use the online tire calculators to figure it out but i haven't been able to find a good match up for larger rear tires than fronts. I'm about 3/4 gone on my current tires and am going to be needing a set here in the next month so i'm trying to figure out what would be a good size to put on the rear of the car and on the front to be a narrower size but still match the overall tire diameter. I was wanting like 285/45 18 on the back something in that width and keep the 245's on the front but its driving me nuts here trying to find a wider rear tire thats not quite a bit taller than the fronts are going to be.
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93 Red Trans Am, LT1, Auto, Custom CAI, Polished TB (mostly just looks nice lol), Flowmaster Catback,
on headers, cam, and a few other goodies to get here. Debating on which electric water pump to use and whether or not MSD is that much better on these cars than the opti. More to come later.
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did you try tirerack.com or discounttiredirect.com?87 GTA: it's winter time, all tore apart
ConElite: "Im 22, have had my TA since I was 21."
"I wont lie, I have a heavy foot, but at the same time I know when its the safest to ring out a gear or 2."
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You have to match the stock tire diameter, or your speedo will be off. You also don't want a large diameter tire in the back - that will be the same as swapping in lower numerical rear gears.
What size were your stock tires - there were two different sizes on the V8 4th Gens:
235/55-16 = 26.18"
245/50-16 = 25.65"
You do not want a 285/45-18 in the back, that would be a 28.0" tire.... wayyyyy too big. Look at the picture of my Formula with the huge slicks on it.... those are 28" tires.
You would use a 285/35-18 = 25.85". For the fronts, if you want to stay with 245's, you would want a 245/40-18 = 25.72". Next question is, what width are your wheels? You can't just mix and match tire sizes and wheel widths.Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motorComment
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ok i think you sort of misunderstood, i do realize not to change heights because of several reasons which were mentioned especially if you go with a taller tire you lose acceleration. I was talking about mostly a larger width. The tires that are on there were matched as closesly to stock size as they can be from what i was told. They are the 245/40 18's the rims are 18x9 front and rear. I was looking at the 285/35 18 but i think it is actually a little taller height than the 245/40's that are on there which i didn't really want to do but will if necessary. I couldn't find anything in a 275 that was very close either it seems like its either all or nothing on that. Also i'm fairly certain the 285's will fit on the 9 inch rims just fine as I have them in a 17 on my stang on a 17x9 rim but i don't think you can go much wider than that. Definately not up to the 325's or anything like that.93 Red Trans Am, LT1, Auto, Custom CAI, Polished TB (mostly just looks nice lol), Flowmaster Catback, on headers, cam, and a few other goodies to get here. Debating on which electric water pump to use and whether or not MSD is that much better on these cars than the opti. More to come later.
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The difference in diameter for the 285/35 and the 245/40 is about 1/8"..... with regard to rolling radius and sidewall height, that's only 1/16" difference. You will not see it.
The diameters I quoted are calculated from the tire size. Those are theoretical sizes. The actual tire diameter is going to vary slight from manufacturer to manufaturer, or even within different tire models from the same manufacturer. But the actual diameter is not going to vary much more then +/- 0.10". Look at the Tire Rack site. It explains everything.
http://www.tirerack.com/
Click on "tires by size". Enter the size you are looking for. You will get a list of all the tires they sell in that size with photo and price. 245/40-18 gives you 100 different tires to choose from.
When you get the screen that lists all the tires, click on the ones you are interested in - "Specs" for the diameter, load capacity, allowable wheel widths, etc.; "reviews", "test results" and survey results to see how the tire is rated.
Your biggest issue is the 9.0" wheel width. In the front, the 245 is going to have the sidewall pretty much flush with the edge of the rim. In the back, the 285 is going to have to bulge out at least 1/2" beyond the rim edge. Most manufacturers will recommend at least a 9.5" wide wheel for the 285. A 275/35-18 would fit correctly on a 9.0" wide wheel, but that tire will be slightly smaller in diameter than the 245/40-18.Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motorComment
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i started looking after the other posts on tire rack it seems they have a little more options than discount tire and I had never been to there site before. I really appreciate all the informative info guys I think I am going to go ahead and go back with just the 245/40's so as not to stretch the tire on the rim. I'm going to go to the shop where the previous owner had purchased the rims and see if there is any chance he could order me two 18x11's for the back and then put the 285's or 295's on there. I found some 295's that would be just a hair higher than the 245's so I think they will be ok. Thanks again ~Heath93 Red Trans Am, LT1, Auto, Custom CAI, Polished TB (mostly just looks nice lol), Flowmaster Catback, on headers, cam, and a few other goodies to get here. Debating on which electric water pump to use and whether or not MSD is that much better on these cars than the opti. More to come later.
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An 11.0" wheel will only fit in the back if it has a 45-50mm offset. Any smaller than that, and the tire is outside the fender, any larger than that, and the inside edge of the tire is against the inner fender liner. If you are interested, I can post a link to a post I put in the FAQ on another site, with details of the mods you may have to make to fit an 11.0" wide wheel.Fred
381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motorComment
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