Hey guys I need new tires and I am wondering wats the max width I can do without rubbing. I have an 07 lsj with sporline springs but I have SS.TC wheels. I could swear I remember seeing someone say they were running 265/40/18 pn their TC wheels because of the wheels offset but I don;t remember if he was lowered or not. I am looking at doing 245 or 255. Any input would be jelpful

 

Any wider than a 235 on a 7.5" wide SS/TC wheel is pointless because your contact patch won't increase anyway. The sidewalls will tip in towards the wheel and lift the outside edges of the tire off the ground. 235/40/18's are perfect. Just pick something sticky such as a Nitto NT05 or Dunlop Direzza Star Spec. I believe both have tread wear rating of 200, but the NT05 only has 7/32" of tread depth while the Star Specs have 10/32".

 

anyone else

 

a treadwear rating of 200 is not good i thought? b/c i see alot of tires that have 400 rating and are a hell lot cheaper

 

I love the premise of this thread. kudos!

I'm a tire engineer, let me clear a few things up.

1. 235 width probably aren't the optimal section width for the cobalt. What is? it depends on what you are trying to do with it. AutoX? no. that whole outer edges lifting off the ground thing: only if they are crappily designed tires and/or over inflated. given a relatively fixed tire OD with increasing section width, aspect ratio will go down, this will reduce the load index of the tires as less sidewall = less load carrying capacity. just an FYI.

2. treadwear rating: very nebulous. lower is worse, higher is better. but each tire manufacturer gets to determine how the relative treadwear rating works (i.e. goodyear treadwear 400 is not equal to hankook treadwear 400)

200 is typical for a summer tire. 400 usually leans toward HP/UHP all season & budget tires.



OP: you are asking about width fitment, not width performance. so you are only concerned with geometry. I highly doubt you'll be able to fit 265 width w/o rubbing. I dont know what the upper limit is. what is your intent with the vehicle?

If you really want to, you can just make the suspension so stiff (stiff springs) that the tire/wheel cant move enough to rub. thats how the street prepare/street mod/prepared AutoX cars run 305's.

 

Bottom line: A sticky 235 is plenty for a car with your mods. A 200 tread wear rating implies that the tire has a soft and sticky compound. A tire with a 400 rating is likely not desirable to the OP because it will be a fairly hard and less grippy compound. Putting too wide of a tire on a wheel can cause a "floating" sensation a the tire shifts from side to side on the wheel. This can greatly reduce turn-in and overall handling performance. A 245 on a 7.5" wheel would be a less than ideal setup for handling purposes, even if it doesn't rub.

 

It would also be outside Tire & Rim Association guidelines and the sidewall would crack in half after 10-20kmiles

 

OI'm going to ask you than because u seem to be the guy to ask. I want a decent set of tires that does well in both wet and dry conditions. I live near L.A. and we tend to have wet winters and with how the roads out here are traction is deffiantly an issue. I don;t do too much racing from the dig so super sticky tires arent soo much needed but i do like to do the canyons a lot and even dabble in autox once in a while so grip is the corners at speed is def an issue

 

Most summer tires have good wet & dry when they are new. All tires lose wet as they get worn down.

for a summer pattern I'd recommend the RE11s. They are the stickiest street tire I've ever used.

for all-season I'd recommend the RE960s. A lot of people think they are summer tires because they say "potenza" on them and grip dry like a summer tire to the inexperienced. They are actually all season tires with damn good snow capability.