After Market Alterations to Honda Fit

We recently got an 08 Honda Fit for our 18 yr old son to drive. He is eager to make changes. Today, I caught him in the garage trying to mount “new” tires on the car that he had bought off Craig’s list: Lexani Extra Load 205/40Z R17 34W. The car came with P195/55 R15 84H. I measured the circumference of both types of tires and the Lexanis appear to be 74 1/8 in. wide, compared to the originals at 72 1/2 in. wide. I know this will affect the odometer and speedometer readings, lower gas mileage and who knows what. I have told him not to put the new tires on the car. He tells me he had this checked out with mechanics who told him an difference would be negligible and this change was okay. Any thoughts out there?

Did he get new wheels as well? Otherwise, there is no way that 17-inch tires will fit on to 15-inch wheels.

The tires came with the rims, which I guess are what you mean by the wheels. I think he bought them because he wanted cool looking rims and a low profile tire.

Who owns the car? If you paid cash, who is on the title? If financed, who is making the payments? If it’s his car, let him do whatever he wants. If it’s your car, remind him that he is borrowing your car and that he can’t make any unapproved changes…

Check and for what fits the vehicle. Both know exactly what fits and doesn’t as they both sell these.

My comment on this is that whoever is responsible for the maintenance and repair of this car has to be financially prepared for increased repair costs as a result of this alteration to the car.

Very low-profile tires, such as these “40-series” tires have so little rubber between the wheel rims and the road surface that potholes and other road irregularities will result in blown tires and bent (unrepairable) wheel rims. Also, components such as ball joints and tie rod ends will take a worse beating because of having so little rubber to absorb road shock, leading to very premature failure of these components.

The trade-off for these very expensive repair problems is:

  1. Improved handling when taking corners at high speed.
  2. The ability to look like a member of an urban gang.

Unless you relish the prospect of having your son drive faster than he should be, and unless you think that looking like an urban gang member is desirable, I don’t see anything positive coming from this alteration. But, since he apparently spent his money on this stuff, there is probably little that you can do, other than making him pay for the inevitable replacement of tires and wheels, and front end repairs.

Eventually, after he has spent many hundreds of $$ that he could have saved, he will probably come to the realization that this alteration to his car was not as cool as he initially thought that it was. says the wheels should fit. However, the wheels probably weigh a lot more than the factory wheels, which will hurt acceleration. If it’s his car(he’s making payments on it and is insured under his own name), let him ghetto it up by putting 20 pounds of chrome on it, just make sure he tells his insurance company about the new rims/tires, otherwise, he’ll be hard pressed to collect on them if he wrecks, or has them stolen(most likely outcome). If you are making payments on it and insured under your name with him as primary driver, let him suffer. The car is under powered as it is, you don’t need another 50 extra pounds on the car to bog it down more.

According to the tire size calcualtor I use, the tires are comparable in size, with a 0.1% difference in overall circumference, given the sizes you posted. The other differences I would worry about are back-set and overall width. Will they rub? Especially with the stock suspension travel? The ride will be harsher, and these tires will wear a lot quicker. Some other things to worry about.

Thank you for all the valuable information. You are great! In answer to some questions, my husband and I bought the car for our son to drive. Our son is not the owner. We can’t afford to let him damage the car, as we’d either have to fix it or I’d become Chauffeur-Mom again, which I am so done with. (Our son works as well as going to school, but doing repairs on the car would ultimatly come out of our pockets one way or the other.) So, enough on parenting. He put the tires on Craig’s List after we argued last night and said today that he has a buyer, for more money than he paid for the tires…here’s hoping…

On to his next desire: He wants to change the air intake to something that he says will give him more power. He says it is like putting on a new air filter and won’t damage the car. Do you have thoughts on this idea?

If he is referring to a K&N filter, there are concerns using an oiled performance filter with damage to Mass Air Flow sensors. If a dry performance filter is used, possibly no problem. But will not create more power as he desires, and will increase engine noise. Also, it may be a basis for Honda to void the engine warranty if a problem crops up. Just some food for thought.

Well this is simple. Haven’t you ever heard of a teenager hunting around for the right, or favorable answer? If you ask a shoe salesman if you need new shoes, of coarse he is going to tell you that you need new shoes. We were teenagers once. We know how teenagers learn most of their most profound lessons: let him find out for himself how expensive gas can be. The worse thing you could do is pay for his gas. Let him find out how expensive things are going to be once he finds out that he has voided warranties because he put bigger tires on the car. If you don’t let this teenager learn some lessons for himself, and pay the consequences he is going to grow up to be a liberal.

And when this is all over and done with, he’ll still have a slow car that is trying to look fast.

There are also concerns with the amount of dirt that goes through those filters. I would not put one on any engine, especially not one that’s still under warranty. Maybe he should limit himself to cosmetic changes?

He’s got a slow vehicle, there’s no real cheap way around that. Let him make alterations to the car AFTER it’s paid for, and in HIS name.

My son said he is talking about a cold air intake system. Is this the same type of system you are referring to that you have said may let dirt in; make the engine noisier; and won’t really improve hp? He thinks he’ll get a hp boost and it will be harmless. Do you have references on this? He thinks he knows everything.

It will improve power slightly at WOT,but without supporting mods like a larger throttle body and larger/recalibtrated MAF sensor, and maybe a larger plenum, and a less restrctive exhaust, it’s mostly for show. According to who you ask, an oil-guaze filter will let more dirt in. I’ve been using them for a while and nothing terrible has happened, but many people don’t like them.

Personally, I don’t trust them for two reasons. If you put too much oil on the filter it can cause problems with the mass air flow sensor in the inlet. If you don’t adequately maintain the filter it can let more dirt into the engine (lots of discussion on the internet about this issue, pro and con). In any event, I would be concerned that this type of modification would cause problems with the warrantee. In the event of an engine failure, it would be easy for the dealer to blame this non-stock air filter.

Modifying the engine with anything other than genuine Honda parts will potentially void the warranty. Do you really want to take a chance on losing the protection of the warranty just so your son can play Speedracer?

He can put the cold air intake (CAI) on after the vehicle’s out of warranty. Until then, it should stay stock. Plus, he’s a teenager - do you really think he’d actually be able to put on a CAI without screwing everything up? It’s easy, but still…

And it may not be harmless. The CAI can suck up water during heavy rains, and hydrolock (ie destroy) the engine, which will certainly not be covered under warranty. You can afford a $3000 engine, right?

We definitely do not want to do anything to damage the car or impact on the warranty and will not allow it. I really appreciate your honest and straightforward responses! My son is going to have to suck it up and accept the car as it is or save his money for a car he can trash. I have to add, he loves the Fit. He just wants to make it “cooler.”