Hey guys,

Been a long time I know but could do with some help with two problems which are pecking my brain.

I've just bought a set of wheels, specs below;

2x 8.5j x 18 et 24
2x 9.5j x 18 et 25

My questions are what tyres sizes would you guys recommend for a 3rd gen firebird with a 1.6" drop and what spacers/adaptors am I going to need to get those wheels right to the edge of the wheel arch?

Thanks in advance guys,
Rich

 

I'm guessing nobody has replied yet because most the answers to your questions will be subjective, based on what your own interests are and what you want to achieve, so there really aren't many specifics anyone can offer you. But a good way to get people replying is for someone to post something that some people don't agree with, so let's try to get this started. Here are a couple of good tools at your disposal to help you figure things out.

One is near the top of this TGO webpage in the "Notices" bar, right below the blue bar that features User CP, FAQ, Members List, etc. Scroll straight up this page ^ , and you should see the link: "Check out the ThirdGen Tire/Rim Calculator." But if you don't see it, then here's a link to it.
https://www.thirdgen.org/forums/tire_rim_calculator.php

The other one is from Rims n Tires and is linked below.
http://www.rimsntires.com/specspro.jsp

But those two sources calculate differently. The TGO calculator will give you fitment based on the width of the rim and the offset, whereas the rimsntires calculator will also take into account the width of the tire, as well as show you the backspacing. So results will appear to vary between the two calculators. But after you've calculated the acceptable offsets and backspacing, then you should be able to arrive at the appropriate adapter thicknesses for your desired fitment.

For adapters, Motorsport-Tech has an excellent database for designing adapters.
http://www.motorsport-tech.com/wheel_adapters.html

Tirerack is a good source for finding comprehensive lists of tire brands, models and sizes.
http://www.tirerack.com/index.jsp

Since you've got staggered wheel sizes, then I'd guess you're also planning on different size tires between front and back. Several different sizes and combinations will work, depending upon the stance you want to achieve and how radical you want to go with the fitment. But without getting too radical and using the factory-installed diameter of 25.7" as a reference, here are some of the more 3rdgen-friendly sizes for those rims:

245/40ZR18(for 8.5 and 9.5 rims, 25.7" diameter)
255/40ZR18(for 8.5 and 9.5 rims, 26" diameter)
265/40ZR18(for 9.5 rims, 26.3" diameter)
275/35ZR18(for 9.5 rims, 25.6" diameter)
275/40ZR18(for 9.5 rims, 26.7" diameter)

With those sizes, the most accurate front/rear combos would be 245/245 or 245/275(35), that second combo being the one I suspect most people would choose. But other combos are 245/255, 245/265, 245/275(40), 255/255, 255/265, or 255/275(40). Most peoples' opinions are likely to vary, so trust your own judgment; it's your car. Also, there would be little noticeable affect on ride height or speedo with any of those combos, so if you like the slightly larger diameter tires, then go for it. Again, it's your car.

It's nice when people who are already using non-stock combinations would post their specific wheels sizes, backspacing, offsets and adapters(if any) and show pics of how it looks on their cars, but people rarely do that. There are even threads where people are asked to state all of that info, but most still won't; I don't know if they're simply oblivious to the questions, or if they, themselves, don't even know what they have. But very few people actually state their combos without leaving anything to question, which is unfortunate, because people can play with those calculators all they want, even get exact dimensions from their actual wheels, but until you actually see or try real fitment, then a close/tight calculated fitment might still end-up being trial-and-error and costly. Whereas, having complete information for tried-n-true fitments would make for excellent reference material. But at least playing with those calculators will give you a good idea of what will probably work for you.

 

That was exactly what i needed, thank you so much for this!

 

18x8 +2mm front 255/35/18
18x9 +7mm rear 275/35/18

 

Your car looks killer! Mine is the same color and until I saw yours, I was going back with stock size wheels and tires. Good job on picking those out. It looks good!

 

looks real good . very nice

 

thanks guys, they weren't my first choice but i like them a whole lot better than my first choice lol.

 

Well I've ordered my tyres. I went with

Front 8.5J 245/40/18
Rear 9.5J 275/35/18

I'll not be fitting them to the car for a bit due to it having no running gear while it's restored but I'll get pics of the wheels with tyres on for you