Pontiac Solstice Forum banner

1 - 15 of 15 Posts

·
Senior Member
Joined
·
5,600 Posts
Discussion Starter #1
The 2860 pound Solstice will wear P245x45s all around. This seems to be too much tire. Would it not be best to minimize unsprung weight. I'm thinking 215 front/225 rear would be about right. Maybe even 225s on 4 corners. But 245s all around seem like too much tire for the base motor, even if it would be right for the 240HP motor.

Am I nuts? :crazy
 

·
Registered
Joined
·
1,844 Posts
:agree (Sort of)
I've got this thing about unsprung weight. Plan in downsizing to lightweight 17" rims. But I don't think I'll make the tires quite as narrow as 215's.
 

·
Registered
Joined
·
527 Posts
I think you have a point. I've got 245/45s on the back of my fiero, and I can't get any more than a chirp out of them. Great for handling, bad for showing off. I can honestly say the Kappa is the first production vehicle where I've considered getting smaller tires...
 

·
Registered
Joined
·
391 Posts
I dont think the tires are to big or to wide or to heavy.
Would it be better if the wheels were lighter? Yes but GM posted some realy great skidpad numbers and swears this is a great track car. It is all about how you set the entire car up, not just wheels. If you were to put smaller tires on the car it probobly would not perform any better. Besides bigger wheels look better and that is needed to sell lots of cars.
I have 215-45 17's in front of my 88FieroGT and 255-45 17's in the rear and the car feels amazing. It is a great car and will for sure out perform the stock wheel sizes I used to have. In the 110+mph range the car is solid as a rock and i can pull MUCH faster speeds on my favorate onramp clover leaf on the way home from work :smile But again it is how the suspension is changed/set up to accomidate the wheels that will determan if the wheels will be better or not. In my case the larger wheels work much better. And my gues is that GM has put a very good wheel package on the KAPPA
 

·
Premium Member
Joined
·
5,206 Posts
I think it's a bit big, myself. I'd downsize, but only as long as the car has large enough brakes. That's my philosophy - think of what you need in brakes, add 15% to the rotor size, then use the smallest wheel you can that will fit.

The additional consideration is max turn angle - you can get better geometry and still maintain a tight max turn radius if you use a larger wheel, so the 18" helps there.

Properly done, the 18" may be the smallest rim you can install without banging into the caliper (just in installing the wheel) or tie rod end (when turning). I doubt you'll be able to fit 16" on, as the rotors are identified as 11.7" for the front (specs card from 04 NAIAS) - adding caliper thickness and such I bet 17" is the smallest and the stuff we don't know (tie rod clearance, etc.) might even prevent that.
 

·
Premium Member
Joined
·
8,901 Posts
If you start making the tire narrower too, you're going to start effecting the skidpad/grip like Rickady88GT mentioned above. If anything I'd go wider in the back for that classic rear wheel drive big rear end look with some wide body fenders. :D
 

·
Registered
Joined
·
113 Posts
The tire and rim sizes are one thing that people loved about the concepts. Most people end up buying larger and wider rims and tires because the factory doesn't put them on to begin with. Everyone was hoping the rims and tires from the concept car would stay, and they have. I say Woo Hoo!
 

·
Mod Emeritus
Joined
·
7,468 Posts
245/45’s are not excessively wide in my opinion. They do sound a little big, but GM has said the base setup on the car is supposed to be equivalent to the sport packages on a competitors cars. I guess part of that means big rubber from the start.

I think the 18’s are overkill on this car. They add extra unsprung weight for the sake of styling and appearance. This is not a big car and doesn’t have a ton of motor at the moment. As solsticeman pointed out, part of the reasoning could be brake/suspension clearance issues. I’ll keep the 18’s, but I would have been just as happy with 17’s on this one.
 

·
Registered
Joined
·
76 Posts
I'm thinking that 18" 245/45 may offer too harsh a ride - unless the General has detuned the suspension for a less sporty ride.
I think that 17" 225/55's would have been a better choice - for the ride quality and for the HP/Torque.
But it is what it is. :rolleyes
 

·
Registered
Joined
·
2,153 Posts
solsticeman said:
I think it's a bit big, myself. I'd downsize, but only as long as the car has large enough brakes. That's my philosophy - think of what you need in brakes, add 15% to the rotor size, then use the smallest wheel you can that will fit.

The additional consideration is max turn angle - you can get better geometry and still maintain a tight max turn radius if you use a larger wheel, so the 18" helps there.

Properly done, the 18" may be the smallest rim you can install without banging into the caliper (just in installing the wheel) or tie rod end (when turning). I doubt you'll be able to fit 16" on, as the rotors are identified as 11.7" for the front (specs card from 04 NAIAS) - adding caliper thickness and such I bet 17" is the smallest and the stuff we don't know (tie rod clearance, etc.) might even prevent that.
For reference, and if my memory serves correctly, my GTP came stock with 10.9" front rotors and 16" rims (incidentally, the stock "torque star" wheels were made by Enkei). I upgraded the front rotors to 11.9-inchers, and the calipers still cleared... barely. I think there was right about 1/4" of clearance. We should be able to get 17's on the Solstice with no problem. Probably even 16's. RWD cars tend to require wheels with less backspacing/offset than FWD.
 

·
Premium Member
Joined
·
5,206 Posts
For how long they last: ***SHRUG***

Who knows, but generally the more margin you have from the max load of the tire (the load rating) vs. the operating load, the longer it should last. The Honda S2000 (basically the same weight as the Solstice) has 87 front and 91 Rear load rating tires.

It looks like the P245/45R18 has a load rating much higher (96?!?). googling the size and "original equipment" digs up the Nissan Maxima - a car much heavier than the solstice.

All season tires generally last longer than summer-only given same size.

Above are ONLY GENERAL STATEMENTS. There are execptions to every generalizations. Being a generalization is like that. IOW: actual mileage may vary.

As far as cost, I think you can find the P234/45R18 Eagle RSA tire for about $179 each or so. $800 for a set mounted and balanced and on yer your way.
 

·
Premium Member
Joined
·
8,901 Posts

·
Mod Emeritus
Joined
·
7,468 Posts
Soul Stiz said:
What will be the lifespan of the tires and how much will they cost to replace?
It appears the stock tires will be Goodyear Eagle RS-A's. They are listed as high performance all season tires. Tire Rack currently has them for $202 a piece, and the runflat version in the same size for $209 per. The treadwear rating for them is 260, which really isn't all that high so they won't last for ever either. Of course, tire life depends a lot on how you drive them too.
 

·
Registered
Joined
·
126 Posts
I went to one of those tire calculator pages to see what the diameter of a 245/45/18 was. To keep your odometer and tranny gears running as intended , you want to keep the rears as close as possible when changing the rim size, providing that the brakes fit.

245/45/18- 26.68 (tire diameter in inches)
245/50/17-26.65
245/55/16-26.61
245/60/15-26.57

225/55/17-26.74
225/60/16-26.63

205/60/17-26.69
205/65/16-26.49

i forgot to see about narrower tires on the 18's..but these are some good references....personally, I like the 245's..give me traction!!
 
1 - 15 of 15 Posts
Top